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ISBN 978-951-802-987-1 (paperback) 978-951-802-988-8 (PDF)ISSN-L 1237-6183ISSN 1237-6183
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Musculoskeletal disorders, disability and work
People and WorkResearch Reports 89
Kari-Pekka Martimo
Musculoskeletal disorders, disability and w
orkK
ari-Pekka Martim
oMusculoskeletal disorders (MSD) are the most important causes of temporary and permanent work disability. The aim of this thesis was to examine the role of work in the disability caused by MSD from various perspectives: primary prevention using lifting advice and devices, perception of work-relatedness, measurement of productivity loss, and secondary/tertiary prevention through ergonomic intervention or part-time sick leave. The original articles include a systematic review, two surveys, a randomised controlled trial, and a study protocol. The results support the early use of a biopsychosocial model for effective management of disability.
89
People and Work
Editor in chief Harri Vainio
Scientific editors Raoul Grönqvist Irja Kandolin Timo Kauppinen Kari Kurppa Anneli Leppänen Hannu Rintamäki Riitta Sauni
Editor Virve Mertanen
Address Finnish Institute of Occupational Health Topeliuksenkatu 41 a A FI-00250 Helsinki Tel. +358- 30 4741 Fax +358-9 477 5071 www.ttl.fi
Layout Juvenes Print / Katja Hakala Cover Picture Sami Rantanen ISBN 978-951-802-987-1 (paperback) 978-951-802-988-8 (PDF) ISSN-L 1237-6183 ISSN 1237-6183 Press Tampereen Yliopistopaino Oy – Juvenes Print, Tampere 2010
MUSCULOSKELETAL DISORDERS, DISABILITY AND WORK
Kari-Pekka Martimo
People and Work Research Reports 89
Finnish Institute of Occupational Health, Helsinki, Finland
DOCTORAL DISSERTATION
Supervisors: ProfessorEiraViikari-Juntura FinnishInstituteofOccupationalHealth Helsinki,Finland
DocentMariAntti-Poika UniversityofHelsinki Helsinki,Finland ProfessorKajHusman FinnishInstituteofOccupationalHealth Helsinki,Finland
Reviewers: DocentMarjaMikkelsson UniversityofTurkuand Päijät-HämeSocialandHealthCareGroup Lahti,Finland
ProfessorHannuVirokannas UniversityofOulu Oulu,Finland
Opponent: ProfessorSakariTola MutualPensionInsuranceCompanyVarma Helsinki,Finland
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ABSTRACT
Musculoskeletaldisorders(MSD)arethemostimportantcauseoftem-poraryworkdisabilityinFinland,andtogetherwithmentaldisorders,theyaccountforthemajorityofpermanentdisabilitypensions.Themostcommonmusculoskeletalproblemintheworkingpopulationislowbackpain(LBP),whichtogetherwithsomeupperextremitydisorders(UED)hasthestrongestscientificevidenceofallMSD,thatworkingconditionshavearoleintheaetiology.
Thisthesisconsistsoffivestudiesrepresentingthreepossibleap-proachestoreducingdisabilityduetoMSDatwork;preventionofthedisordersbyreducingtheirwork-relatedriskfactors(primarypreven-tion),preventionofdisabilityasaconsequenceoftheexistingMSD(secondaryprevention),andpreventionoftheexacerbationofdisability(secondaryandtertiaryprevention).Thestudiesexamineworkactivityasariskfactor,butalsoasanindicatorofthelevelofdisabilityandasanopportunityforrehabilitation.
Themethodsusedinprimarypreventiontochangeworkingroutinesarenotsupportedbyevidencegatheredinasystematicreviewshow-ingthatwidelyadaptedtraininginliftingtechniquesdoesnothelptopreventLBP.Earlierstudiesingeneralhaveshownonlymodesteffectsofwork-relatedinterventionsintheprimarypreventionofMSD.Intermsofsecondaryprevention,thecross-sectionalsurveyrevealedthatmanyworkerswithMSDconsiderthemselvesaspartiallyabletoworkinsteadofeithertotallyableorunable.Theyalsofrequentlyperceivetheirmusculoskeletalhealthproblemsasbeingrelatedtowork,andthebeliefwasshowntocorrelatewithself-assesseddisability.Manyworkers,however,considerthattherearepossiblechangesthatcouldbeinitiatedintheworkplacetogivethemsupportinworkingdespitetheirMSD.
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ABSTRACT
Accordingtoanothersurvey,medicallyverifiedUEDcausesignificantproductivitylossatwork,evenwhentheemployeesdonotneedsickleavebecauseofthesymptoms.ThislostproductivityisusuallynotincludedineconomicevaluationsoftheconsequencesofMSDatwork.IntheassessmentofemployeeswithMSD,productivitylossshouldbetakenintoconsiderationinadditiontocollectingdataonself-assessedwork-relatednessofthedisorder.Ifthedisordercannotbemedicallycured,thenthechallengeforallparties,i.e.theemployee,employerandhealthserviceprovider,istoaccommodateworkinordertoavoiddeteriorationofthesymptomsduetowork,and,ontheotherhand,impairmentofworkoutputbecauseofthesymptoms.
Earlyergonomicinterventiontogetherwithadequatemedicalcarerestoreddecreasedon-the-jobproductivityassociatedwithUEDbetterthanmedicalcarealone.Thisrandomisedcontrolledtrialaddstotherelativelyscarcebodyofworkontheeffectivenessofergonomicinterven-tions.TheresultsalsoencourageoccupationalhealthpersonneltotryforanearlyinteractionwiththesupervisorandtoanergonomicworksitevisitifUEDisthemaincomplaintoftheemployee.Comparedtoregularhealthcarepractices,thestudyinterventionwasinitiatedatanearlierstage.MostoftenintheacutephaseofMSD,apurelybiomedicalmodelofdisabilityisapplied.Onlywhenthedisabilitybecomesprolonged,aremorework-orientedactionstaken.Accordingtothepresentresults,however,ergonomicinterventionislesseffectivewhenappliedatamoreseverestageofUED.
BasedonthefindingthatpartialworkabilityiscommonamongemployeeswithMSD,thebeneficialeffectsofmodifiedworkonreturntoworkinearlierstudies,andthepositiveattitudestopart-timesickleavereportedinotherNordiccountries,arandomisedcontrolledtrialwasdesignedandinitiatedtocomparepart-timesickleaveandconven-tionalsicknessabsenceinthemanagementofMSD.Duringpart-timesickleave,theemployeeisadvisedandsupportedtocontinueworkingsothattherecoveryprocessisnotendangered,andbothworkingtimeandworktasksaremodifiedincollaborationwiththesupervisor.Theresultsofthistrialcanbeexpectedin2011.
ThisthesisshowsthatdisabilitycausedbyMSDcanbemanagedeffectively,especiallyintheoccupationalhealthservices.Despitetheevidencethatliftingadvicehasnoeffectivenessinprimaryprevention,
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ABSTRACT
thesecondstudydiddetectencouragingresultsatthelevelofsecondaryprevention.ThisapproachchallengesthemanagementofworkerswithMSDutilisingonlythebiomedicalmodel.Theresultsencouragetheadaptationofabiopsychosocialmodel,wherethemainfocusisshiftedfrompossibleanatomiccausestowardsmorecomplexsystemsofworkdisability.Inthismodel,theimportanceofstakeholderinteractions(forexample,family,supervisor,co-workers,employer,andinsurancecompany)isstressedtogetherwiththecrucialroleoftheindividual.
ThemajorityofbarriersandfacilitatorsofstayingatworkdespiteMSDarerelatedmoretopsychosocial,workplaceandmanagementissuesratherthantothephysicaldisorderitself.Therefore,thediseasediagnosisperspectiveinthemanagementofMSDhastobesupplementedbyadisabilitydiagnosis,byinvestigatingitscausalpsychosocialandenviron-mentalfactors.Theapproachsupportseffectivedisabilitymanagementstrategies,whichpreventunnecessarysicknessabsenteeismandallowemployeestoremainproductiveatworkdespiteMSD.
6
YhTEENvETO
OhimeneväätyökyvyttömyyttäaiheuttavatSuomessaenitentuki-jaliikuntaelinsairaudet.Yhdessämielenterveyshäiriöidenkanssaneovatyleisinsyypysyviintyökyvyttömyyseläkkeisiin.Tavallisinliikuntaelinvai-vatyöikäisilläonalaselkäkipu.Kaikistaliikuntaelinvaivoistaselkäkivunjajoidenkinyläraajasairauksiensuhteenonenitennäyttöä,ettätyölläjatyöolosuhteillaonmerkitystänäidenvaivojensynnyssä.
Tämäväitöskirjakoostuuviidestäosatutkimuksesta,jotkaedustavatkolmeamahdollisuuttavähentääliikuntaelinsairauksistaaiheutuvaatyökyvynlaskua;ennaltaehkäisemällävaivojavähentämälläniidentyö-peräisiäriskitekijöitä(primaaripreventio),vähentämälläolemassaolevistavaivoistaaiheutuvaatyökyvynlaskua(sekundaaripreventio)sekäestä-mällätyökyvynlaskunpaheneminen(sekundaari-jatertiaaripreventio).Väitöskirjakäsitteleetyötoimintaariskitekijänä,muttamyöstyökyvynmittarinajakuntoutumismahdollisuutena.
Primaaripreventiossakäytetyttyöskentelytapoihinkohdistuneetmenetelmättulevatkyseenalaistetuiksitässätutkimuksessa.Järjestel-mällisessäkirjallisuuskatsauksessaosoitetaan,ettälaajaltikäytössäolevanostotekniikoidenopettamineneiautakaanehkäisemäänalaselkäkipuataakankäsittelyssä.Aikaisemmatkintutkimuksetovatyleensäosoitta-neet,ettätyöperäisilläinterventioillaonvainvaatimattomiavaikutuksialiikuntaelinvaivojenprimaaripreventiossa.Sekundaaripreventionosaltapoikittaistutkimuksessaosoitetaan,ettämonettyöntekijätovatmieles-täänliikuntaelinvaivastahuolimattaosittaintyökykyisiäsensijaan,ettäpitäisivätitseäänjokotäysintyökykyisinätaityökyvyttöminä.Heidänmielestäänliikuntaelinvaivatovatuseinmyöstyöperäisiä,millätutki-muksessaosoitetaanolevanyhteyttäitsearvioituuntyökyvynlaskuun.
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YHTEENVETO
Monientyöntekijöidenmielestätyöpaikallaonkuitenkinmahdolli-suuksiasellaisiinmuutoksiin,jotkaauttavatheitäselviytymääntyössäänliikuntaelinvaivastahuolimatta.
Toisenpoikkileikkaustutkimuksenmukaanlääkärintoteamaylä-raajavaivaaiheuttaamerkittäväätuottavuudenalenemaatyössämyössilloin,kuntyöntekijäeioleoireidenvuoksisairauslomantarpeessa.Tätätuottavuudenalenemaaeiyleensähuomioida,kunarvioidaanliikuntaelinvaivojenaiheuttamiataloudellisiaseurauksiatyössä.Lii-kuntaelinoireisentyöntekijäntutkimisessatulisihuomioidasairaudestaaiheutuvatuottavuudenlaskusamoinkuintyöntekijänomaarviovaivantyöperäisyydestä.Vaikkasairauttaeivoilääketieteellisestiparantaa,työn-tekijän,työnantajanjaterveydenhuollonyhteinenhaasteonmukauttaatyötäniin,ettävältetäänsekätyöstäaiheutuvaoireidenpaheneminenettäoireistajohtuvatyöntuloksenheikkeneminen.
Yhdistämällävarhaisiaergonomisiatoimenpiteitäasianmukaiseenlääketieteellisenhoitoonvoidaanpalauttaayläraajavaivoihinliittyväalen-tunuttyötuottavuusparemminkuinpelkällälääketieteellisellähoidolla.Tämäsatunnaistettukontrolloitututkimustukeetähänmennessävä-häistänäyttöäergonomistentoimenpiteidenvaikuttavuudesta.Tuloksetmyöskannustavattyöterveyshenkilöstöäolemaanvarhaisessavaiheessayhteydessäesimieheenjakäymääntyöpaikalla,mikälityöntekijänpää-ongelmaonyläraajavaiva.Verrattunaterveydenhuollontavanomaiseentoimintaantutkimuksentoimenpiteetaloitettiinvarhaisemmassavaihees-sa.Useimmitenliikuntaelinvaivanakuutinvaiheenhoidossasovelletaanvainpuhtaastilääketieteellistämallia.Vastakuntyökyvynlaskupitkittyy,ryhdytääntyöhönliittyviintoimenpiteisiin.Tulostenmukaanergono-misettoimenpiteetovatkuitenkinvähemmänvaikuttavia,josniihinryhdytäänvastayläraajavaivanmuututtuavakavammaksi.
Osittainentyökykyonyleistäliikuntaelinvaivoistakärsivillätyönteki-jöillä.Lisäksiaikaisemmintutkimuksissaonosoitettu,ettämukautetullatyöllävoidaannopeuttaatyöhönpaluutasairauslomanjälkeen.KunvielämuissaPohjoismaissaonkuvattumyönteistäsuhtautumistaosa-aikaiseensairauspoissaoloon,viidesosajulkaisukuvaasatunnaistetunkontrolloiduntutkimuksen,jossaverrataanosa-aikaistajaperinteistäsairauspoissaoloaliikuntaelinsairauksienhoidossa."Osasairausvapaan"aikanatyöntekijääohjataanjatuetaanjatkamaantyössääntoipumistavaarantamatta,kun
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YHTEENVETO
sekätyöaikaaettätyötehtäviämuokataanyhteistyössäesimiehenkanssa.Tämäntutkimuksentuloksetovatkäytettävissävuonna2011.
Tämäväitöskirjaosoittaa,ettäliikuntaelinvaivoistaaiheutuvaatyö-kyvynlaskuavoidaanhoitaatehokkaastierityisestityöterveyshuollossa.Vaikkatutkimustenmukaannosto-opetusprimaaripreventionaeiolevaikuttavaa,toinenosajulkaisuosoittaa,ettäsekundaaripreventiossasaadaankannustaviatuloksia.Tämähaastaapelkänlääketieteellisenmallinkäytönjakannustaabiopsykososiaalisenmallinhyödyntämiseenliikuntaelinvaivoistakärsivientyöntekijöidenhoidossa.Päähuomiosiirretäänmahdollisistarakenteellisistasyistäkohtityökyvyttömyyteenliittyviämonimutkaisempiajärjestelmiä,joissapainotetaansekäsosiaa-lisiavuorovaikutussuhteita(esim.perhe,esimies,työkaverit,työnantajajavakuutusyhtiö)ettäyksilönkeskeistäasemaa.
Suurinosaliikuntaelinvaivankanssatyössäjatkamisenesteistäjamahdollistajistaliittyyenemmänpsykososiaalisiintekijöihinsekätyöhönjajohtamiseenkuinfyysiseenvaivaansinänsä.Siksidiagnoosinlisäksiliikuntaelinvaivojenhoidossaontutkittavatyökyvyttömyyttäaiheuttaviajaylläpitäviäpsykososiaalisiajaympäristöönliittyviätekijöitä.Tämälähestymistapaluomahdollisuuksiatukeatyökykyä,välttäätarpeetonsairauspoissaolojaedesauttaatyöntekijöidentyössäjatkamistatuottavastiliikuntaelinvaivastahuolimatta.
9
ACKNOWLEDgEMENTS
ThisthesisistheresultofmyworkconductedintheFinnishInstituteofOccupationalHealthstartingatthebeginningof2005.TheCentreofExpertise"HealthandWorkAbility"anditsteamof"Work-relatedDiseases"havebeenmybestpossibleschoolandsupportinmyaspira-tiontohigheracademiclevel.IamforevergratefultoDocentHelenaLiira,whoinitiallysuggestedthatIwouldcombineresearchandpracticalwork.IamalsothankfultotheFinnishInstituteofOccupationalHealththatmadeitpossibletotakethiscrucialstepintotheintriguingworldofmusculoskeletalresearch.
Themainprerequisitesforadoctoralstudenttosucceedarethesupervisors.IcouldneverhavemadethisstepwithoutProfessorEiraViikari-Juntura,whoalwayswasavailablewhenIneededher.Iadmirethepositiveenergyshecantransmiteveninsituationswhenherappro-priatecorrectionswerefollowedbyhoursofextrawork.Theeffortwasalwaysworthdoing,becausetheresultwasbothapersonallygratifyinglearningexperienceandamuchbetteroutcome.
Ialsooweverymuchtomyothersupervisors,DocentMariAntti-PoikaandProfessorKajHusman.Theybothhavebeenpersonallyveryimportanttome,notonlyduringthepresentendeavour.Bothcolleagueshavebeenmytutorsfromthebeginningofmycareerinthefieldofoc-cupationalhealth,andthereforewithoutthemIcouldnothavebecometheoccupationalhealthprofessionalthatIam.
WhatIappreciatemostinmycolleaguesandco-authorsistheteamspiritthatwehavesharedduringthepreparationoftheoriginalarticles.IamespeciallygratefultoJosVerbeek,MD,PhD,whotaughtmethefinessesoftheCochranemethodology,aswellastoProfessor
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ACKNOWLEDGEMENTS
JaroKarppinenandDocentEsa-PekkaTakala,fortheinspiringdiscus-sionsaroundmusculoskeletalresearch.IwanttothankalsoRahmanShiri,MD,PhD,forbeingalwaysreadytosharehisexpertiseinthestatisticalanalyses.IhavealsobeenveryluckytoworktogetherwithHelenaMiranda,MD,PhD,whoseideasaboutmusculoskeletalpainanditsmanagementhaveinspiredmenotonlytoincludetheminthescientificworks,butalsotoimplementtheminpracticeasanoc-cupationalphysician.
Icouldnothavedoneallthiswithoutmycolleaguesandco-authorsLeenaKaila-Kangas,JohannaKausto,RitvaKetola,MarttiRechardt,RitvaLuukkonen,MerjaJauhiainen,AndreaFurlan,andPaulKuijer.Iwanttoexpressmywarmestthankstothem,aswellastoProfessorHilkkaRiihimäki,whoneverfailedtogiveherpositiveencouragementtomeasajuniorresearcher.Another"seniorcitizen",whomIwishtothank,isDocentKirstiLaunis.Fromher,Ilearntthatsometimestheresultsarelimitedbythechosenmethod,and,therefore,researchisnotsimplylookingforthetruth,butrathertryingtofindthepathtothetruth.
Iamalsogratefultotheofficialreviewers,DocentMarjaMikkels-sonandProfessorHannuVirokannas,fortheirvaluablecommentsforimprovingthemanuscript,aswellastoEwenMacDonaldforrevisingthelanguage.
IthasbeenimportantthatIhavebeenabletosharemyworktimebe-tweenresearchandpracticalworkasanoccupationalphysician.Withoutthepositiveattitudeofmysupervisorsandemployers,firstAriHimmaatM-realCorp.andsubsequentlyTapioVirtaatMehiläinen,Icouldnothavehadtheopportunitytoconductthisacademicwork.Therefore,Iwanttoexpressmygratitudetobothofthem,withoutforgettingallthesupportthatIhavereceivedfrommycolleaguesatMehiläinenOc-cupationalHealthCare.
Sometimestheboundarybetweenworkandleisureisveryvague.Ihaveenjoyedenormouslythescientificdiscussions(andalsothelessscientificones)withJormaMäkitalo,MD,PhD,JuhaLiira,MD,PhD,andProfessorPeterWesterholm.Inaddition,SirkkuVuorma,MD,PhD,andDocentMattiHöyhtyäaremyoldestfriends,whosestepsIhavefollowedfirstinfolkdancingandtheninPhDstudies.Fortunately
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ACKNOWLEDGEMENTS
Ihavebeenblessedwithmanydearfriends,whohavesupportedmeinalltheirownways.Thankyouforthat!
Finally,thereasonforeverythingismyfamily,mymotherToini,fatherJaakko,andbrotherArto.IamalsothankfulformyextendedfamilyinVaasafortheirfriendship.Thelastandthewarmestthanksgotomypartner,Sami.YourloveandcareistheairthatIbreathe.Thisworkisdedicatedtoyou.
Helsinki, May 3, 2010
Kari-Pekka Martimo
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ABBREvIATIONS
CCT controlledclinicaltrial(nonrandomised)CI confidenceintervalCTS carpaltunnelsyndromeFIOH FinnishInstituteofOccupationalHealthGEE generalizedestimatingequationICF InternationalClassificationofDisability, FunctioningandHealthLBP lowbackpainMSD musculoskeletaldisordersOH(S) occupationalhealth(services)OR oddsratioQQ QuantityandQualitymethodRTW returntoworkRCT randomisedcontrolledtrialUED upperextremitydisordersWHO WorldHealthOrganisation
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LIST Of ORIgINAL PUBLICATIONS
I MartimoKP,VerbeekJ,KarppinenJ,FurlanAD,TakalaEP,KuijerPPFM,JauhiainenM,Viikari-JunturaE(2008).Effectoftrainingandliftingequipmentforpreventingbackpaininliftingandhandling:systematicreview.BMJ336(7641):429–31
II MartimoKP,VaronenH,HusmanK,Viikari-JunturaE(2007).Factorsassociatedwithself-assessedworkability.OccupMed(Lond)57(5):380–2.
III MartimoKP,ShiriR,MirandaH,KetolaR,VaronenH,Viikari-JunturaE(2009).Self-reportedproductivitylossamongworkerswithupperextremitydisorders.ScandJWorkEnvironHealth35(4):301–8.
IV MartimoKP,ShiriR,MirandaH,KetolaR,VaronenH,Viikari-JunturaE(2010).Effectivenessofanergonomicinterventiononproductivityofworkerswithupperextremitydisorders:–arandomisedcontrolledtrial.ScandJWorkEnvironHealth36(1):25–33.
V MartimoKP,Kaila-KangasL,KaustoJ,TakalaEP,KetolaR,RiihimakiH,LuukkonenR,KarppinenJ,MirandaH,Viikari-JunturaE(2008).Effectivenessofearlypart-timesickleaveinmusculoskeletaldisorders(Studyprotocol).BMCMusculoskel-etalDisorders9:23doi:10.1186/1471-2474-9-23
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CONTENTS
1.INTRODuCTION........................................................ 16
2.REVIEWOfCONCEpTS............................................... 19 2.1.Musculoskeletaldisorders........................................ 19 2.1.1.General...................................................... 19 2.1.2.Lowbackpain............................................. 19 2.1.3.upperextremitydisorders............................ 20 2.1.4.Work–relatedmusculoskeletaldisorders......... 21 2.2.Disability............................................................... 22 2.2.1.Biomedicalmodel........................................ 23 2.2.2.Biopsychosocialmodel................................. 24 2.2.3.Othermodels.............................................. 25 2.3.Disabilityandwork................................................. 26 2.3.1.Sicknessabsenteeism................................. 27 2.3.2.Sicknesspresenteeism (productivitylossatwork)............................ 29 2.3.3.Returntowork............................................ 31 2.3.4.Work–relatedinterventions........................... 31
3.pREVIOuSSTuDIESONMuSCuLOSKELETAL DISORDERS,DISABILITYANDWORK........................... 34 3.1.Work–relatedriskfactorsof musculoskeletaldisorders........................................ 34 3.1.1.Background................................................ 34 3.1.2.Lowbackpain............................................. 38 3.1.3.upperextremitydisorders............................ 41 3.1.4.Work–relatedinterventionsin preventingmusculoskeletaldisorders............. 44 3.2.Work–relatedriskfactorsofsicknessabsence............ 46 3.2.1.General...................................................... 46 3.2.2.Lowbackpain............................................. 47 3.2.3.upperextremitydisorders............................ 51 3.2.4.preventionofsicknessabsence causedbymusculoskeletaldisorders.............. 51 3.3.Work–relateddeterminantsofsicknesspresenteeism... 54 3.3.1.preventionofsicknesspresenteeism associatedwithmusculoskeletaldisorders...... 58 3.4.Determinantsofreturntowork................................ 59 3.4.1.Workerperceptionsandexpectations............. 60 3.4.2.Workenvironmentandworkorganisation....... 61 3.4.3.Roleofthemedicalprovider........................ 64
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CONTENTS
4.CONCEpTuALfRAMEWORKOfTHESTuDY................... 67
5.STuDYquESTIONSANDHYpOTHESES......................... 71
6.MATERIALANDMETHODS........................................... 73 6.1.Studypopulations.................................................. 73 6.2.Methods................................................................ 74 6.2.1.Systematicreview(StudyI)......................... 74 6.2.2.Surveys(StudiesII–III)............................... 75 6.2.3.Randomisedcontrolledtrials(StudiesIV–V)..... 77 6.3.Statisticalanalyses................................................. 79 6.3.1.Systematicreview(StudyI)......................... 79 6.3.2.Surveys(StudyII–III)................................. 79 6.3.3.Randomisedcontrolledtrials(StudiesIV–V).... 80
7.RESuLTS.................................................................. 82 7.1.Trainingandliftingdevicesforpreventing backpain(StudyI)................................................ 82 7.2.factorsassociatedwithself–assessed workability(StudyII)............................................. 86 7.3.Self–assessedproductivitylosscaused byupperextremitydisorders(StudyIII)................... 89 7.4.Effectivenessofanergonomicintervention onproductivityloss(StudyIV)................................. 92 7.5.Earlypart–timesickleavein musculoskeletaldisorders(StudyV)......................... 96
8.DISCuSSION............................................................ 97 8.1.Mainfindings......................................................... 97 8.1.1.primarypreventionoflowbackpain andrelateddisability................................... 97 8.1.2.factorsassociatedwithperceiveddisability...... 98 8.1.3.productivitylossasanindicatorofdisability..... 100 8.1.4.Secondarypreventionofdisability................. 101 8.1.5.Comparisonoftwodisability managementmethods................................. 102 8.2.Methodologicalconsiderations.................................. 103 8.2.1.Studydesigns............................................. 103 8.2.2.Studypopulations....................................... 106 8.3.Implicationsforfutureresearch............................... 108 8.4.policyimplicationsandrecommendations.................. 109 8.5.Conclusions........................................................... 111
REfERENCES...............................................................113
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1. INTRODUCTION
Oneofthemostcrucialaspectsoflifeishealth.Thisdoesnotmeanonlytheabsenceofsymptoms,illnessandmorbidity(WHO2001).Healthalsomaintainscapacitytoattainone’sowngoalsthroughtarget-orientedactions,i.e.,paidorunpaidwork.TheWorldHealthOrganisation(WHO)hasclassifiedhealthandfunctioningusingthreedifferentdo-mains:bodyfunctionsandstructures,activity(levelofcapacity;whatapersoncandoinastandardenvironment),andparticipation(levelofperformance;whatapersoncandointheirusualenvironment)(WHO2001).IntheInternationalClassificationofFunctioning,DisabilityandHealth(ICF),theterm“functioning”isusedtorefertoallbodyfunc-tions,activitiesandparticipation.Similarly,theterm“disability”referstoallimpairments,activitylimitationsandparticipationrestrictions.
Disabilityisexplainedas“somethingthatrestrictsorlimits”.There-fore,theFinnishtranslation“työkyvyttömyys”(workincapacity)fortheterm“workdisability”canbeconsideredasmisleading.Itreinforcesthefalseunderstandingthatworkdisabilityisadichotomousfactor,i.e.youhaveeitherfullcapacity(“työkykyinen”)oryouareentirelyincapacitated(“työkyvytön”).ThisisnotsupportedbyICF,whichviewsdisabilityandfunctioningasinteractionsbetweenhealthconditions(diseases,disor-dersandinjuries)andcontextualfactors(externalenvironmentalandinternalpersonalfactors)(figure1).Disabilityinvolvesdysfunctioningatoneormoreofthethreedomains(impairments,activitylimitations,andrestrictedparticipation).Restrictionsandbarrierstoperformanceoffunctionalactivitiesorrolesinwhichapersonengagesinthecontextofhisorherlifearealsoconsideredtohaveaninfluenceuponhealthoutcomesandthehealthrecoveryprocess.ICFhasutilizedabiopsycho-socialmodelofdisability(explainedinmoredetailsinchapter2.2.2.).
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1INTRODuCTION
Health condition
(disorder or disease)
Personal Factors
EnvironmentalFactors
Body Functions& Structure
ParticipationActivity
FigurE 1. interactions between the components of iCF (WHO 2001)
AccordingtoICF,thedisabilityprocessinitiatedbyahealthconditionisinfluencedbybothenvironmentalandpersonalfactors.Environmentalfactorscanincludesocialattitudes,architecturalcharacteristics,legalandsocialstructure,aswellasclimateandterrain.Thepersonalfactorsaregender,age,copingstyles,socialbackground,education,profession,pastandcurrentexperienceofhealthconditions,overallbehaviourpattern,personality,andotherfactorsthatinfluencetheperceptionofdisabilitybytheindividual.
Disabilitydoesnotmeantotallossoffunctioninginanyofthethreedomains.Despiteofamedicalcondition(forexample,seropositivityforHumanImmunodeficiencyvirus),apersonmaybefullyfunctionalinboththeactivityandparticipationdomains.Inaddition,andparticularlywithparticipation,restrictions(problemsanindividualmayexperienceininvolvementinlifesituations)canbeconsideredasproblemscreatedbyanunaccommodatingphysicalenvironmentasaresultofattitudesandotherfeaturesofthesocialenvironment.
Latelythepositiveeffectsofworkhavegainedincreasingattention(Waddelletal.2006).Workoftenplaysaroleinpromotingbothphysicalandmentalhealth:physicalactivity(forexample,work)isusuallyas-sociatedwithimprovementinphysicalcapacity,whilegoalachievement,
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1INTRODuCTION
socialinteractions,andself-realisationinworkaresourcesofsatisfactionandenhancedself-esteem(WHO1985).Therefore,insteadofleavingworklife,peoplewithdisabilitiesshouldbeencouragedtocontinueinemployment,providedthatworkisadaptedtohumangoals,capacitiesandlimitations,andoccupationalhazardsareundercontrol.
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2. REvIEW Of CONCEPTS
2.1. Musculoskeletal disorders
2.1.1. general
Themusculoskeletalsystemcomprisesofbonesandjointswiththeiradjacentstructures,aswellasmuscles,tendonsandligaments.Thisstudyisconcernedwithdisabilitycausedbyorassociatedwithmusculoskeletaldisorders(MSD).InFinland,MSDarethemostimportantcausesoftemporarydisability(lastinglessthanoneyear)(Kansaneläkelaitos2008).MSDalongwithrespiratoryinfectionsarethemostcommonreasonsfortheuseofprimaryhealthservices.Inaddition,MSDandmentaldisordersaccountforthemajorityofpermanentdisabilitypensionsinFinland.
”Disorder”inthisstudyreferstoanycomplaint,symptomordiseaseofthemusculoskeletalsystem.Complaintisanexplicithealthproblemexperiencedbyanindividual.Disease,ontheotherhand,isaclinicallyverifiableentitythatisdetectedinaclinicalexamination.Standardizedclinicalexaminationprotocolsformanycommonmusculoskeletalsymp-tomsareavailableinordertoachieveamorereliableandcomparablediagnosis(Sluiteretal.2001).
Lowbackpain(LBP)andupperextremitydisorders(UED)arescru-tinizedinthisthesis,sinceLBPisthemostcommonmusculoskeletalcauseofdisabilityandthereisstrongevidenceofwork-relatednessforbothUEDandLBP(Punnettetal.2004).
2.1.2. Low back pain
LBPisdefinedaspaininthelumbarand/orglutealregionwithorwith-outradiationtothelowerextremities.Itisoftencategorisedaccording
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tothedurationofthesymptoms:acutepainwithlessthan4–6weeks,sub-acutebetween4–6and8–12weeksandchronicaspainofmorethan8–12weeksofduration.However,"long-lasting"or"prolonged"shouldbepreferredinsteadof"chronic"inordertoavoidunnecessarylabellingoftheemployeewithLBPbeing"chronically"ill.
VariousdiagnosesandpathologicalconditionsmaymanifestwithLBP.However,theoverwhelmingmajorityofbackpaincasesremainnonspecific.About85 %ofpatientswithisolatedLBPinprimarycarecannotbegivenanyprecisepathoanatomicaldiagnosis,andtheassocia-tionbetweensymptomsandimagingresultsisweak(Deyoetal.2001).Inabout3 %ofcasesthereasonsforLBPareneoplasia,infection,visceralpainorsystemicdisease.
Despitethefactthatbackpainisnotalifethreateningcondition,itconstitutesamajorpublichealthproblemintheWesternindustrialisedsocieties.LBPaffectsalargenumberofpeopleeachyearandisthecauseofseverediscomfortandfinanciallosses(Maniadakisetal.2000).Oneimportantfeatureofworkerswithnonspecificbackpainisthatasmallproportionofcases(<10 %)accountsformostofthecosts(>70 %)(Dionneetal.2005).Duetoitshighprevalence,backpainisaleadingreasonforphysicianvisits,hospitalisationsandotherhealthandsocialcareserviceutilisation.
TheseverityandtypeofbackpainchangewithageeventhoughLBPiscommonalreadyinadolescenceandearlyadulthood(Mikkels-sonetal.1997).Itbecomesmoreseverearoundtheageof40,showingdifferentdevelopmentofnonspecificandradiatingLBP.Accordingtoalongitudinalstudyofarepresentativepopulation,moderateaswellasmajornonspecificLBPdeclineswithage,whereastheincidenceofmajorradiatingLBPincreaseswithage(Shirietal.2010).
2.1.3. Upper extremity disorders
SofttissueMSDoftheupperlimbandshoulderregioncompriseaheterogeneousgroupofconditionsrangingfromspecificupperlimbconditions,likedeQuervain'stenosynovitis,epicondylitis,rotatorcufftendinitis,andcarpaltunnelsyndrome(CTS),tonon-specificregionalpainsyndromes.Labelssuchas"repetitivestraininjury","cumulativetraumadisorder"and"work-relatedupperlimbpain"havebeenoften
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used(Walker-Boneetal.2005),butshouldbeappliedwithcaution,becausetheyalreadyincludeanassumptionoftheaetiologyofthedisorder.Inaddition,"non-specificforearmpain"hasbeenadoptedasthediagnosticlabelforpatientspresentingwithforearmpainwithoutphysicalsigns(Walker-Boneetal.2005;vanTulderM2007).SomeagreedsystemsofclassificationofUEDhavebeendevelopedtoimprovethequalityofepidemiologicalresearch(Harringtonetal.1998;Sluiteretal.2001;Helliwelletal.2003).
UEDarecommonintheworkforce.Inapopulation-basedstudyofFinnishadults,theprevalenceofaclinicallydiagnosedUEDwashighestforrotatorcufftendinitisandCTS(both3.8 %),followedbylateralepicondylitis(1.1 %),bicipitaltendinitis(0.5 %),andmedialepicondylitis(0.3 %)(Shirietal.2007).InFinland,1070work-relatedMSDwerereportedtotheregisterofwork-relateddiseasesin2007representing17 %ofallconfirmedorsuspectedoccupationaldiseases(Karjalainenetal.2009).Themostcommondiagnoseswererelatedtotheupperextremities;epicondylitis(halfofallcases),tenosynovitis,andCTS.
2.1.4. Work-related musculoskeletal disorders
MSDaremultifactorialintheirorigin,andwhenaffectingworkers,theycanbework-relatedinanumberofways:MSDmaybepartiallycausedbyadverseworkconditions;theymaybeaggravated,acceleratedorex-acerbatedbyworkplaceexposures;andtheymayimpairworkcapacity.Itisalsoimportanttorememberthatpersonalcharacteristics(includinggeneticfactors),aswellasenvironmentalandsocioculturalfactorsusu-allyplayaroleasriskfactorsforwork-relateddiseases(WHO1985).Inaddition,duetothehighprevalenceandrecurrenceratesofMSD(especiallyLBP),cautionhasbeenadvisedinrelatingthesedisordersexclusivelytotheworkplace(Werneretal.2009).
AccordingtotheFinnishWorkandHealthSurveyconductedin2006(Kauppinenetal.2007),28 %ofthe2229interviewedemployeesreportedlong-termorrecurrentphysicalorpsychologicalsymptomsthathadbeencausedorworsenedbyworkduringthelastmonth.Dependingonthelocationofthesymptoms,63–91 %ofthosewithmusculoskeletalsymptomsconsideredthemtoberelatedtowork.
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Asystematicreviewshowedthatpotentiallywork-relateddiseasesarecommoningeneralpractice(Weeversetal.2005).Highprevalenceratesofpotentiallywork-relateddiseaseswerefoundforLBP,neckpainandshoulderpain.AccordingtotheresultsofaNorwegiansurvey,themajorityofcaseswithMSDwereassessedasbeingwork-relatedbyboththestudyparticipantsandtheexperts:80 %versus65 %forpainintheneckorshoulderregionand78 %versus72 %forarmpain(Mehlumetal.2009).
IthasbeenarguedintheNetherlandsthattoolittleattentionispaidtothepossiblework-relatednessofhealthcomplaints,andthatthiscanbeamajorcauseofsicknessabsenceanddisability(Buijsetal.2005).Ifthephysicianscannotrelatethepatients’healthcomplaintstoworkfactors,theyareatriskofmakinganinadequateassessmentortheymaymisseffectivetherapeuticmeasures.Thiscanleadtounnecessarylongsicknessabsenceperiods,and,evenpossibly,permanentdisability.
2.2. Disability
Disabilityisstudiedinthisthesisfromtheperspectiveofproblemsintheparticipationatwork,“occupational/workdisability”.Theterm“dis-ability”,however,willbeusedforsimplicity.Thespecialfocusisontherelationofdisabilityandwork,howworkaffectstheemployee’shealthandfunctioningatwork,andhowamedicalconditioncanimpactontheemployee’sabilitytocontinueworking,payingspecialattentiontocontextual,personalandenvironmentalfactors.
Occupationalorworkdisabilityisusuallydefinedastimeoffwork,reducedproductivity,orworkingwithfunctionallimitationsasaresult(outcome)ofeithertraumaticornon-traumaticclinicalconditions(Schultzetal.2007b).
Theredoesnotexistonesinglemodelofdiagnosisandrehabilitationofpain-relatedoccupationaldisability,butmany,oftencompetingandconflicting,modelscurrentlyexist.Thecoreissueistoselecttherightmodelfortherightservicerecipientattherighttime.
Inthecontextofworkdisability,observationalstudieshavedem-onstratedthatadversedisabilityoutcomesareinextricablylinkedwithcommunicationfailuresbetweentheemployeeandthecareprovider,and
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descriptionofsuccessfulprogrammesoftenciteeffectiveorimprovedcommunicationasanimportantelementintheirsuccess(Pranskyetal.2004).Therefore,effectivecommunicationcanbeseenasaprerequisiteforsuccess,regardlessofthespecificapproachtodisabilitymanagementandprevention.
2.2.1. Biomedical model
Thebiomedical model (alsocalledasthe"diseaseparadigm")isthepre-dominantframeworkusedbyalargegroupofhealthcareprofessionalsasmosthealthcaresystemsarestillbasedonapurelymedicalmodelofillnessandinjury.Inthismodel,illnessisconsideredtobeaconse-quenceoftheill-functioningofthehumanorganismasa"biologicalmachine",andthediseaseisdescribedasalinearsequencefromcausefactortopathology,tosymptomsormanifestations(Schultzetal.2000).Thesecondtenetofthebiomechanicalmodelholdsthatsymptomsanddisabilityaredirectlyrelatedto,andproportionateto,theseverityofbiologicalpathology.Thereforeaccordingtothistheory,eliminationofpathologicalcauseswillinevitablyresultincureorimprovement.Interventionstudiesemployingthisapproachhavefocusedontheroleofspecificmedicaltreatmentsorclinicalapproachesintendedtopreventprolongeddisability(Pranskyetal.2004).
Communicationinthebiomedicalmodelisoftenunidirectional(physiciantoemployerandpatient),notinteractive,asphysiciansissuedefinitivepronouncementsaboutcause,diagnosisandfunction.Inad-dition,patientsusuallyadheretothebiomedicalmodeldiffusedinthemedia,meaningthattheirexpectationsmaybeinconsistentwithothermodelsthatwouldbestsuittheircondition(Loiseletal.2005).
Consideringthecomplexnatureofpain,solelyfocussingonbiomedi-calpathologyresultsinalackofconsiderationofthemultidimensionalnatureofthephenomenon,thevarietyofreactionstopain,andthechangingnatureofinjuryandpainovertime(Schultzetal.2000).Thisexclusiveattentiononobjectivelyidentifiedpathologynegatestheim-portanceofpatient-centredmeasuresofpain,symptomsanddisability."Objective"measuresofpathology,however,havebeenshowntopredictdisabilityratherpoorly,andapathophysiologicalexplanationcannotbeofferedinallMSD.Thesearchforwhatisusuallyanelusive"medi-
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calexplanation"ofpaininmostcasesprolongsthediagnosticprocessneedlessly.Asaresult,thismodel,whenappliedtononspecificpainconditions,canincreasechronicityandhumansufferingandimposeafinancialburdenonhealthcareandcompensationsystems.
Forthosekindsofinjuriesandillnesseswherehealingprocessesarehighlypredictableandtheriskofre-injuryislow(minorlacerations,trauma,orfractures),thebiomedicalmodelperformswell(Pranskyetal.2004).Thismodelisrelevantwithrespecttomedicaldecisionmaking,particularlywithregardtouncomplicated,physicalinjuriesorpainorbothinitsacutestages,aswellasintheidentificationofmedical"redflags",i.e.,rulingoutofseriousmedicalconditions,suchastumours,infectionsandfractures(Schultzetal.2000).
2.2.2. Biopsychosocial model
Fromanepidemiologicalperspective,itappearsthatnon-clinicalfac-torsaremorelikelythanclinicalatexplaininglong-termdisabilitycases(Loisel2009).Therefore,itisnotaquestionofimprovingclinicalcareinordertoachievebettertreatmentresults.Thebiopsychosocial approachhasbeenmodifiedinmanydifferentformsandisgenerallythemostcommonlyconsideredandconsensualframeworkforunderstandingthemultidimensionalaspectsofmanyhealthproblems(Schultzetal.2007b).Thebiopsychosocialmodelrecognizesthattherelationshipsbetweenpain,physicalandpsychologicalimpairment,functionalandsocialdis-abilityarefarfromsimple;painandresponsetoMSDarecomplexandinteractingphenomena(Schultzetal.2000).Thisapproachdemandsaconceptualshiftfromthelinearwayofthinkingofthebiomedicalmodeltoanopensystemperspective.
Researchonthistopichasyieldedsubstantialevidenceonthede-terminantsofworkdisability.Thesedeterminantscanbelinkedtotheworker(personal),workplacedesignororganisation(workplace-related),healthcaresystem,compensationsystemorthenatureofthelocalcultureandsociety(Loisel2009).Theparadigmshiftfromabiomedicaltoabiopsychosocialmodelofdisabilitytransfersresponsibilityforoutcomesfromthehealthcareprovider-patientrelationshiptoamulti-playerdeci-sion-makingsystemwhichisinfluencedbycomplexprofessional,legal,administrative,andcultural(societal)interactions(Loiseletal.2005).
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Basedontheprinciplesofthebiopsychosocialmodel,inthecase management model,theclientisanactiveparticipantintherehabilita-tionprocess,andtherehabilitationteamonlyfacilitatesthisprocess(Schultzetal.2000).Thetherapeuticfocusistherestorationoffullfunction,notsymptomremovalor"cure",andtherestorationofemploymentstatuswithminimaldelayisoneofthemajorgoalsoftreatment(Schultzetal.2000).Earlyinterventiondesignedtorestorephysicalorrolefunction,increaseactivitylevels,andtoachieveworkmaintenanceorworkre-entryisconsideredtoexpeditethereturntowork(RTW)process.
Casemanagementisessentialwhentheclient'streatmenthastobecoordinated,plannedandmonitored.Thisemphasisstemsfromthebeliefthatthelongerthepainanddisabilitypersist,themoredifficulttheywillbetotreat.Thereforeidentificationofthosefactorsthatpredictpoorprognosisforcontinueddisabilityandidentificationofthoseworkersathighriskforcontinuedworkdisabilityareimportantcomponentsofearlyintervention(Schultzetal.2000).
2.2.3. Other models
Themajortenetoftheinsurance model (alsocalledasforensic,compensa-tionorthe"perverseincentives"model)isthatclaimantswhoanticipatefinancialbenefitsthroughcompensation,pendinglitigation,specialservicesorconsiderations,suchasjobtransferorreducedworkload,arelikelytobedishonestabouttheirsymptoms(Schultzetal.2000).Thereisastrongmoralisticelementinthismodelwhereitisnecessarytoclearlydifferentiatebetween"honest"and"dishonest"claimants.Theinsurancemodelnurturesaclimatewhereintheclaimantmustvigorouslyproveandproveagainhisorherdisabilitywithobjective,verifiable,repeatablemedicalevidenceofimpairment.
Anothersubgroupofthemedicalmodelisthepsychiatric modelwiththebasictenetthatpainiseitherorganicorpsychologicalinitsorigin(Schultzetal.2000).Painthatcannotbeattributedtophysicalcausesmustbepsychological,andpatientswithundiagnosed,intractablepainareapsychologicallyhomogenousgroup.Thediagnosisofamentaldisordercanentitleapatienttoreceiveservicesandbenefitsthatmightnototherwisehavebeenavailable.However,thepsychiatricframework
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forpainhasproventobeineffectiveforrehabilitationandcanbediag-nosticallymisguiding(Schultzetal.2000).
Thephysical rehabilitation modelcanalsoberelatedtothebiomedi-calmodel,becauseitsfocusindisabilitymanagementandpreventionstrategiesisonimprovedphysicalconditioning(Pranskyetal.2004).ThismodelassumesthatRTWoutcomescanbeimprovedbymuscle-strengtheningexercisesinaclinicalorworkplacesettingthatsimulatesactualworkingconditions.Onelimitationofthismodel,however,isthatworkenvironmentsmaybedifficulttosimulateespeciallywhen,inreallife,psychosocialandorganisationalfactorsaresignificantcontributorstodisability(Pranskyetal.2004).Inaddition,thetraditionalrehabili-tationmodelseemsone-sided:disabilitymanagementsimplyfocusesonimprovingworkercapabilitiestomatchjobdemandswithoutanythoughtofredesigningormodifyingjobstomatchworkerlimitations.
Ajob-match modelfordisabilitymanagementusesananalyticalstrat-egytoassessthematchbetweenanindividualwithfunctionallimitationsandaparticularjob(Pranskyetal.2004).Thismodelmayproveusefulforworkplaceaccommodationeffortswherebiomechanicalrequirementsareuniform,andergonomicrisksarerelativelyeasytodefine(forexample,assembly-lineworkers,keyboardoperators).Thisapproachassumesthattheworkercapabilitiesareeasilyquantifiedinrelationtojobtasks,allphysicaldemandsarecapturedbyphysicalmeasures,andthatdemandsarestaticovertime.Theseassumptionsarerarelyrealisticinthemodernworkenvironment.Inaddition,thejob-matchmodeldoesnotaddresspsychosocialfactorsorhowanemployee-jobmismatchistranslatedintotheappropriateaccommodation(Pranskyetal.2004).
2.3. Disability and work
Theprocessoffallingill,beingabsentfromwork,recoveringandthenreturningtoworkhasbeenrepresentedschematically(EuropeanFoun-dationfortheImprovementofLivingandWorkingConditions1997).Theonsetofdisabilityisviewedintermsofanimbalancebetweenthepersonandtheenvironment(figure2).Dependingontheopportunityandneedforabsenteeism("absenteeismbarrier"),healthproblemsmayresultinabsenteeismandincapacitytowork.RTWdependsonthe
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courseoftheillnessandthe"reintegrationbarrier",whichreferstothetotalityoffactorswhichaffectthecourseoftheillnessandRTW.Thiswholeprocessisinfluencedbyindividualfactors,companyandworkplacefactors,aswellasfactorspertainingtothesurroundingsociety.
Thedefinitionsofdurationofoccupationaldisabilityrangefromcumulative,asinthedurationofalldayslostfromworkstartingwiththedateoftheonsetofsymptoms,throughcategorical,forexampleRTWstatus(yes/no),tocontinuous,suchastimetoRTW.Inaddition,predictorsofdisabilityandpredictorsofRTWoftendiffer(Schultzetal.2007b).
2.3.1. Sickness absenteeism
Whenamedicalconditionissevereenoughitimpedesjobperformancetothedegreethattheemployeeisnotabletocontinueworkingbecauseofexcessivelylowfunctionalcapacityinrelationtotheexplicitorimplied
CapacityAbsenteeism
barrierreintegration
barrier
BalanceHealth
problemsreturn to
workAbsence of
work
Workload
individual factors
company/workplace factors
societal factors
FigurE 2. The process of becoming ill, being absent from work, recovering and return to work (European Foundation for the improvement of Living and Working Conditions 1997)
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jobdemands.Otherreasonsforabsencefromworkarethattheexposureatworkmakesthesymptomsworseormedicalcareandrehabilitationrequiresthattheemployeecannotbepresentatwork.Whentheemployeeabstainsfromworkingbecauseofadisablingmedicalcondition,thisiscalledsick-nessabsence(orsickleave),andthephenomenonsicknessabsenteeism.
Sicknessabsenceismeasuredbyaskingtheemployeehowmuchtimeheorshehasmissedfromworkbecauseofillhealth.Theotherandmorereliablealternativeistorelyonstatisticscollectedbyemployersonhowmuchtimetheemployeeshavebeenabsentfromworkbecauseofillness.Ifthestatisticsarenotavailable,self-reporteddatahavebeenfoundtobereliableandvalid,whentherecallperiodsareshort(i.e.,1–2weeks)(Mattkeetal.2007).Evenwhentherecallperiodisuptooneyear,theagreementbetweenthenumberofself-reportedandthenumberofrecordedsicknessabsencedaysisrelativelygood(Ferrieetal.2005;Vossetal.2008).Iftherecallperiodsarelonger,theresultsneedtobeviewedwithcaution.
Thefollowingbasicmeasureshavebeensuggestedforassessingsickleaves:frequency(totalnumberofsickleaveperiods/allemployees),length(sick-leavedays/sick-listedpersons), incidence(newspells/(numberofemployeesxnumberofdaysminusallsick-leavedays)),cumulativeincidence(numberofemployeeswithsickleaveperiods/allemployees),andduration(sick-leavedays/sickleaveperiods)(Hensingetal.1998).Itisalsobeneficialtoseparateshortandlongtermabsenceperiods,asonlymedicallycertified(longterm)absenceshavebeenshowntoserveasaglobalmeasureofhealth,butnotshortselfcertifiedabsences(Kivimäkietal.2003).
InalargeprospectivecohortstudywithFinnishmunicipalemploy-ees,themeasuresofsicknessabsence(longtermabsenceperiodsandsickdays)wereshowntobestrongpredictorsofallcausemortalityandmortalityduetocardiovasculardisease,cancer,alcoholrelatedcauses,andsuicide(Vahteraetal.2004).Medicallycertifiedabsencesduetocirculatorydiseases,surgicaloperations,andpsychiatricdiagnoses(butnotMSD)wereassociatedwithincreasedmortalityalsoamongBritishcivilservants(Headetal.2008).
InasurveyamongFinnishlabourunionmembers(Böckermanetal.2009),absenteeismcausedbyanyreasonwaspositivelyassociatedwithparticipationinshiftorperiodwork,whereasregularovertime
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wasassociatedwithlesssicknessabsenteeism.Thepossibilitytostayathomeuptothreedayswithoutanycertificatewasnotassociatedwithanyincreaseinsicknessabsenteeism.
2.3.2. Sickness presenteeism (productivity loss at work)
Healthdisordersdonotcausemerelyabsencefromwork,butalsode-creasedon-the-jobperformancewhileatwork,whichiscalled"sicknesspresenteeism".Theshorterterm"presenteeism"willbeusedinthistexttodescribeproductivitylossatworkduetoMSD,evenifpresenteeismcanalsobecausedbyfactorsotherthanhealth(forexample,organisa-tionaldysfunctionordistractingdomesticproblems).Asystematicreviewcovering37studiesconcludedthatseveralhealthconditions,suchasasthmaandallergies,aswellashealthriskfactors,likeobesityandphysi-calinactivity,areassociatedwithpresenteeism(Schultzetal.2007a).
However,themeasurementofproductivityanditslossatworkisdifficult.Insomeprofessions,liketelephonecustomeroperators,pro-ductivitycanbemeasuredobjectivelyusingkeystrokesorthenumberofreceivedtelephonecallsastheindicator.Ontheotherhand,particu-larlyininformationandservice-typeoccupationstheoutputatworkisdifficulttoquantify.Therefore,amultitudeofworkplaceproductivitymeasurementinstrumentshavebeencreatedandevaluated(Mattkeetal.2007).Nonetheless,themostcommonapproachofmeasuringpresenteeismisassessmentofperceivedimpairment,accomplishedbyaskingemployeeshowmuchtheirillnesseshindertheminperformingcommonmental,physical,andinterpersonalactivitiesandinmeetingjobdemands(Mattkeetal.2007).
Theconsequencesofpresenteeismhavebeenstudiedfromtheor-ganisationalaswellasfromtheindividualperspective.IntheNorthAmericanliterature,thefocushasbeenonhealthandproductivityasabusinessstrategy(Goetzeletal.2007).Thisapproachisbasedonthefindingthathealth-relatedproductivitycostsaresignificantlygreaterthanmedicalorpharmacycostsalone(onaverage2.3to1),andthatchronicconditionssuchasdepression/anxiety,obesity,arthritis,andback/neckpainareespeciallyimportantcausesofproductivityloss(Loeppkeetal.2009).Sinceemployersaretheultimatepurchasersofhealthcareservices
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forthemajorityofemployeesintheUnitedStates,thesefindingshavepromptedemployerstodevelopandevaluatethecost-effectivenessofhealthandproductivityinterventions.
IntheEuropeanliterature,moreattentionhasbeenpaidtothecon-sequencesofpresenteeismattheindividuallevel,basedonthefindingsthat63–83 %ofemployeesreportedhavingworkeddespiteillnessonatleastoneoccasionduringthepreviousyear(Bergströmetal.2009).Sicknesspresenteeismseemstobemoresensitivetoworktimearrange-mentsthansicknessabsenteeism,eventhoughthedirectionofcausalitycouldnotbeexploredinacross-sectionalstudy(Böckermanetal.2009).
AccordingtoaSwedishreviewonsicknessabsenteeismandpresentee-ism,nostudieswerefoundontheconsequencesofsicknesspresenteeismfortheindividual(SBU2004).Productivityloss,however,iscommonbothbeforeandafterperiodsofsicknessabsence(Brouweretal.2002).Perhapsthereforepresenteeismhasbeenassociatedwithmoresicknessabsenteeisminseveralstudies.ASwedishprospectivestudy(Bergströmetal.2009)concludedthatworkingdespitethefactthattheemployeefeltthatsickleaveshouldhavebeentakenwasastatisticallysignificantrisk(relativerisk1.4–1.5)forfuturesickleaveofmorethan30days.Inthesamestudy,however,takingsickleaveduringthebaselineyearwasanevengreaterriskfactorforfuturesickleave;relativeriskwas1.5–5.4dependingonthenumberofdaysonsickleave.Therefore,sickleavemaynotbeanalternativetosicknesspresenteeism,iffuturesicknessabsenteeismistobeprevented.
Alargeprospectivecohortstudywitha3-yearfollow-upamongBrit-ishcivilservantsshowedthattheincidenceofseriouscoronaryeventswastwiceashighamongemployeeswhodidnottakesickleavedespitepoorperceivedhealthatbaseline,comparedtothose"unhealthy"employeeswithmoderatelevelsofsicknessabsenteeism(Kivimäkietal.2005).Thisphenomenonhasbeenlaterstudiedthoughithasnotbeenpossibletodetectanyevidencethatworkingwhileillwouldactasashort-termtriggerforcoronaryevents(Westerlundetal.2009).Accordingtotheauthors,twopotentialexplanationsremain.Workingwhileillmightcontributetoacumulativepsychologicalburdenwithpathophysiologicconsequences,orthatsicknesspresenteeism,insteadofbeingacausalagent,isonlyamarkerofalifestyleinwhichsymptomsareignoredandmedicalcareisnotsought(Westerlundetal.2009).
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2.3.3. Return to work
RTWcanbeconceptualisedasthe"process"ofreturninganinjuredworkertowork(forexample,graduatedRTWorjobaccommodation)orasthemeasurablefinalcommonoutcomeofdisability:thestatusofworkingornotworking(Schultzetal.2007b).RTWasanoutcomemayinvolvereturntothepre-injuryemployerorthepre-injuryjob,withorwithoutaccommodation(Schultzetal.2007b).Consequently,theperspectiveson,andmeasurementsof,RTWinresearchandpracticevarywidelyanddependonthestakeholdersinvolvedintheevaluationprocess.
Insteadoffocusingonthecharacteristicsofworkdisability,themainemphasisshouldbeontheactionsassociatedwithsuccessfulworkre-sumption.Therefore,RTWhasbeenpresentedasanevolvingprocesscomprisingoffourkeyphases:offwork,workre-entry,retention,andadvancement(Youngetal.2005).TheendofeachRTWphasemarkstheachievementofimportantRTWoutcomes:theabilitytoattemptworkre-entry,theabilitytoperformsatisfactorily,theabilitytomaintainemployment,andtheabilitytoadvanceinone'scareer.
SicknessabsenteeismandRTWaredependentoneachother;disabilitycanbemeasuredbothasprolongedsickleaveanddelayedRTW.Therefore,itissometimesdifficulttodifferentiatewhetherthestudyhasbeenconcernedwithsicknessabsenteeismorRTW.Inthisthesis,thestudieshavebeencategorisedaccordingtothemainout-comemeasure;thelengthofsicknessabsenceorsuccessfulRTW.Theformerstudiesarelabelledasstudiesonsicknessabsenteeism,andthelatterasstudiesonRTW.
2.3.4. Work-related interventions
Thedefinitionof"work-relatedintervention"usedinthisthesishasbeenadoptedfromarecentCochranereviewoninterventionsfocusingonchangesintheworkplaceorequipment,workdesignororganisation(includingworkingrelationships),workingconditionsorworkingenvi-ronment,andoccupational(case)managementwithactivestakeholderinvolvementof(atleast)theworkerandtheemployer(vanOostrometal.2009).
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AccordingtoColeetal(Coleetal.2003),workplaceinterventionstoreducemechanicalexposurescanbeexecutedateightdifferentlevels:
1. Businesssector(forexample,ergonomicbestpractices)2. Organisationorcompany(forexample,ergonomicpolicy,audit)3. Plantorworkplace(forexample,ergonomicchangeteams)4. Lineordepartment(forexample,reorganisedflow)5. Workgroup(forexample,safetyclimatetraining,jobrotation)6. Job(forexample,jobenlargement,regularbreaks)7. Worker(forexample,ergonomictraining,workstationadjustment)8. Taskortool(forexample,sharpeningimprovements,newtrimming
tools,liftassists)
HealthcareactivitiesaimedatpreventingMSDandrelateddisabil-itycanbedividedintothreetheoreticalcategories(NationalResearchCouncilandInstituteofMedicine2001).Primary preventionoccurswhentheinterventionisundertakenbeforeworkersatriskhaveacquiredaconditionofconcern,forexample,educationalprogramstoreducethenumberofnewcases(incidence)ofLBP.Secondary preventionoccurswhentheinterventionisundertakenafterindividualshaveexperiencedtheconditionofconcern,forexample,introductionofjobredesignforworkerswithsymptomsofCTS.TertiarypreventionstrategiesaredesignedforindividualswithchronicallydisablingMSD;thegoalistoachievemaximalfunctionalcapacitywithinthelimitationsofthatindividual'simpairments.
Similarthree-levelapproachhasbeenintroducedtodisabilityman-agement,inwhichthemainfocusisnotontheclinicalsymptomsbutonrelateddisability(Loisel2009):(A)Primarypreventionconsistsoflookingatthework-relatedfactorsinordertopreventnotonlysymp-tomsordisordersbutalsorelateddisability;(B)Secondarypreventionincludespayingattentiontotheworkerswithsymptomsordisorders,andinstigating actionstohelptheseworkersrecoverorimprovetheirworkingsituationinsteadofsickleaveorlowerproductivityatworkduetohealthproblems;(C)Tertiarydisabilitypreventionisconceptualisedbyinterventionsthatpreventunnecessaryprolongationofsicknessab-senteeismandsupportsafeRTW.
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Organisationalexperimentstoimproveoccupationalhealthareusu-allyregardedaslaboratory-basedexperimentsinthenaturalsciences,evenifinorganisationstheconditionsaretotallydifferent.Theprerequisitesoftemporalpriority,controloverimportantvariables,andrandomal-locationofsubjectstotreatmentorcontrolgroupsareusuallyhardtofulfil(Griffiths1999).Intheircomprehensivereviewoninterventionstoreducework-relatedMSD(Silversteinetal.2004),SilversteinandClarkereportedthatitwasextremelydifficulttorandomiseengineeringcontrolsinmultipleworkplaces,andmucheasiertorandomisepersonalbehaviour(exercise,education,medicaltreatment).Manystudieshavebeenconfrontedwithchangesinworkplacesthatareunplannedbytheresearchersandbeyondtheircontrol.Stableworkplaceswithlargenum-bersofworkersperformingthesameworkarelargelyathingofthepast.
Quiteevidentlytheavailableresearchondisabilityismethodologi-callydifferentfromtheepidemiologicalstudiesonoccupationalrisksofMSD.Thelatterarescientificallymorerigorousinconfirmingcause-and-effectrelationshipsandallowingprediction.Studiesondisability,however,includelesstangiblefactors,suchasthedesign,management,andorganisationofwork,whereitisunrealistictoexpectthattherewouldbeanaturalscientificparadigmtoexplainthesehighlycomplex,constantlychangingsystemsandtopredictthespecificeffectsonindi-vidualbehaviourandhealth(Griffiths1999).Thishasledtothefactthatstudiesondisabilityhaveappliednotonlyquantitativebutalsomorequalitativemethodologies.
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3. PREvIOUS STUDIES ON MUSCULOSKELETAL DISORDERS, DISABILITY AND WORK
Thefollowingreviewisdescriptiveandprimarilybasedontheresultsofrecentlypublishedreviewsgatheredfromthemainoccupationalhealth(OH)journals.Inaddition,selectedindividualstudieshavebeenincludediftheyhavebeenpublishedrecently,ortheyareconsideredespeciallyinterestinginthecontextofthisthesis.
3.1. Work-related risk factors of musculoskeletal disorders
3.1.1. Background
Athoroughcomprehensionofthecausalassociationbetweenoccupa-tionalexposuresandMSDisnecessaryifonewishestoestablishoc-cupationalguidelinesfortheprimarypreventionofMSD,toidentifypotentialworkmodificationsforthesecondaryprevention,andtopro-videguidanceforthestakeholdersinvolvedintheprocessoflong-termdisability.This,however,isnotasimpletasktoaccomplish.
Epidemiologicalresearchreliesupontheuseofdiagnosticcriteriacapableofseparatingstatesofdiseasewithdifferentcauses,prognosis,orresponsetotreatment(Walker-Boneetal.2005).Inmoststudiesonbackpain,theoperationalisationbasedonthesymptomreportingdoesnotallowexaminationoftheriskfactorsfordifferentgroupsofbackpain,classifiedbasedoncharacteristicssuchastheduration,frequency,
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3pREVIOuSSTuDIESONMuSCuLOSKELETALDISORDERS,DISABILITYANDWORK
intensity,andlocalisationofthepain(Hoogendoornetal.1999).LatelyaDelphiconsensusprocesswasusedinordertoreachasubstantialagree-mentonLBPoutcomesthatwouldbecombinableintoameta-analysis(Griffithetal.2007).
ManystudiesinthefieldofMSDarecross-sectionalsurveysrelyingonself-reportedsymptomsastheindicatorsofMSD.Thisapproachhastwomajoraspectswhichneedtobetakenintoconsideration.First,theweaknessincross-sectionalstudiesisthedifficultytodistinguishcauseandeffect,aswellasriskfactorsthatprolong(andnotcause)thedisorder.Second,thedeterminantsofspecificMSDseemtodifferfromthoseofsubjectivecomplaintswithoutclinicalfindings(Mirandaetal.2005).Suchcomplaintsmaybeindicatorsofadversepsychologicalandpsychosocialfactorsratherthanthepresenceofanunderlyingpathologiccondition.
Informationonexposuresinthestudiesisoftenself-reportedandnotsupportedbyobjectiveobservationsormeasurements.Non-random(biased)associationsmayariseifsubjectswithorwithoutsymptomshaveadifferentrecallofexposures,orifthosewithexposuresthatworrythempaymoreattentiontotheirsymptoms(Viikari-Junturaetal.1996;Walker-Boneetal.2005).Inaddition,theassessmentmethodsforpsy-chosocialriskfactorsvary,becausethereisapoorconsensusabouthowthesefactorsshouldbemeasured.Severalreviewshavenotedthatthereisalackofconsistencyinhowkeyaspectsofthepsychosocialenviron-ment,suchasjobdemands,autonomy,andworkplacesupportandjobsatisfaction,aremeasuredinindividualstudies(Macfarlaneetal.2009).Thereisalsovariationinboththedomainsinvestigatedandtheapproachtocollectingdomain-specificdata.
Physicalloadisassumedtohavebothanacuteandacumulativeeffectontheoccurrenceofbackpain(Hoogendoornetal.1999).Aloadthatexceedsthefailuretoleranceofthetissue,evenifonlyappliedonce,cancausebackpain.However,thecumulativeloadresultingfromlowermagnitudeloadsmaybeevenmoreimportant.Insuchcases,backpainisassumedtobetheresultofarepeatedapplicationofloadsorthelong-termapplicationofasustainedload.
PainisthemainsymptominmostMSDandtheobjectivefindingsareusuallybasedonfunctionalrestrictionscausedbypain.Painperception,ontheotherhand,isdependentonmanyindividual,psychologicaland
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socialfactors,insteadofpathophysiologicalaspects.Therefore,anygivenriskfactorisunlikelytocausemusculoskeletalsymptomsormedicallyverifiabledisordersinallemployees,butthecontextpartlydetermineswhetherdisturbingpainisperceivedornot.
Theeffectsoftheworkenvironmentonhealthmaybemediatedbyatleasttwopathways,assuggestedinthemodeldepictedinfigure3(Coxetal.1994).Ithasbeenarguedthatthephysico-chemical andthepsycho-physiological mechanismsdonotofferalternativeexplanations,buttheyarepresentandinteracttodifferentextentsinallsituations.Whilemanyoftheeffectsofthephysicalenvironmentaremediateddirectlybythephysico-chemicalmechanism,anxietyandfearaboutthatenviron-mentmayalsohaveapsycho-physiologicalimpact.Inturn,theeffectsonhealthofthepsychosocialandorganisationalenvironmentsarelargelymediatedbypsycho-physiologicalprocesses,thoughcertainissues,likeworkplaceviolence,mayhaveadirecteffectthroughphysicalinjury.
indirect effects and moderation of effects
of physical hazards
Occupational health
Hazards in physical work environment
directeffects
Physico-chemicalpathway
mediation
indirect effects and moderation of effects of psychosocial and
organisational hazards
Cognitive and psycho-physiological pathway
mediation
Hazards in psychosocial and organisational work environments
FigurE 3. Work environment and occupational health: a model suggested by Cox and Ferguson (1994)
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3pREVIOuSSTuDIESONMuSCuLOSKELETALDISORDERS,DISABILITYANDWORK
Fourexplanationsfortheassociationbetweenpsychologicalworkcharacteristicsandmusculoskeletalsymptomshavebeenproposed(Hoogendoornetal.2000);(1)psychosocialworkcharacteristicscandirectlyinfluencethebiomechanicalloadthroughchangesinposture,movementandexertedforces;(2)psychosocialworkcharacteristicsmaytriggerphysiologicmechanisms,suchasincreasedmuscletensionorincreasedhormonalexcretionthatmayinthelongtermleadtoorganicchangesandthedevelopmentorintensificationofmusculoskeletalsymp-tomsormayinfluencepainperceptionandthusincreasesymptoms;(3)psychosocialfactorsmaychangetheabilityofanindividualtocopewithanillnesswhich,inturn,couldinfluencethereportingofmusculoskeletalsymptoms;(4)theassociationmaywellbeconfoundedbytheeffectofphysicalfactorsatwork.
Insystematicreviewsontheeffectivenessofthework-relatedinter-ventions,fivelevelsofevidencehavebeenusedtosummarisetheresults.MostreviewsadapttheclassificationsuggestedbytheCochraneCol-laborationBackReviewGroup(vanTulderetal.2003).Accordingtothisclassification,"strong evidence"referstoconsistentfindingsamongmultiplehighqualityrandomisedcontrolledtrials(RCTs);"moderate evidence"referstoconsistentfindingsamongmultiple lowqualityRCTsand/ornonrandomisedcontrolledclinicaltrials(CCTs)and/oronehighqualityRCT;"limited"referstoonelowqualityRCTand/orCCT;"conflicting"referstoinconsistentfindingsamongmultipletrials(RCTsand/orCCTs);and"no evidence"referstothefactthatnoRCTsorCCTshavebeenidentified.Thisclassificationwasmodifiedquiterecently(Furlanetal.2009)labellingthelevelsaccordingtothequalityoftheevidenceas"high","moderate","low","verylowqual-ity",or"noevidence".
Inconclusion,researchonMSDfacesmanychallengesrelatedtotheappropriatestudymethodsandoutcomes,exposureandsymptomverifi-cation,andthetheoreticalmodelsexplainingtheeffectsofbothphysicalandpsychosocialexposuresandtheirinteraction.Thereisalargebodyofevidencealreadyavailable,butmorehighqualityresearchisdefinitelyneeded.IftheassociationbetweenworkandMSDisrelatedtoagreaterlikelihoodofsymptomsanddisabilitythanthedisorderitself,thisshouldbereflectedinthepreventionactivitiesandergonomicmeasures.
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3.1.2. Low back pain
PreviousresearchhasfoundoveronehundredpotentialriskfactorsforLBP(Bakkeretal.2009).AsummaryoftheoccupationalriskfactorsofLBPdiscussedherearepresentedintable1.
Table 1. Work-related risk factors of lbP
Risk factors Reference
Physical risk factors
Manual material handling, including lifting, moving, carrying, and holding loads, as well as bending and twisting; whole-body vibration
Patient handling, high level of physical activity
Whole-body vibration, nursing tasks, heavy physical work, working with one's trunk in a bent and/or twisted position
Occupational bending or twisting
(Hoogendoorn et al. 1999)
(Hoogendoorn et al. 1999)
(Bakker et al. 2009)
(Wai et al. 2009)
Psychosocial risk factors
Low social support in the workplace
High job demands and low job satisfaction
Low job control and low supervisor support
(Hoogendoorn et al. 2000)
(Macfarlane et al. 2009)
(Kaila-Kangas et al. 2004)
Accordingtoareviewofphysicalloadduringworkasariskfactorforbackpain(Hoogendoornetal.1999),thereisstrongevidencethatmanualmaterialhandling,includinglifting,moving,carrying,andholdingloads,aswellasbendingandtwistingareriskfactorsforbackpain.Themagnitudeoftheriskestimate(relativerisk/oddsratio)rangedfrom1.5to3.1formanualhandling.Thereisalsostrongevidencethatwhole-bodyvibration
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isariskfactorforbackpain(effectestimate4.8),andmoderateevidencethatpatienthandlingandahighlevelofphysicalactivityareriskfactorsforbackpainwiththemagnitudeoftheriskestimatesrangingfrom1.7to2.7(forpatienthandling)andfrom1.5to9.8(forheavyphysicalwork).Inthesensitivityanalysis,however,noevidencewasfoundfortheeffectofheavyphysicalload(Hoogendoornetal.1999).
TheresultsbyHoogendoornetal.arechallengedbyamorerecentsystematicreview.Thisincluded18prospectivecohortstudiesevaluatingspinalmechanicalloadduringworkand/orleisuretimeactivitiesasriskfactorsfornonspecificLBPinpatients(>18yearsofage)freeofLBPatbaseline(Bakkeretal.2009).TheconclusionwasthatthereareseveralhighqualitystudieswithconsistentfindingsthatLBPisnotassociatedwithprolongedstanding/walkingorsittingatwork.Accordingtothisreview,evidenceisconflictingforwhole-bodyvibration,nursingtasks,heavyphysicalwork,andworkingwiththetrunkinabentand/ortwistedpositionasriskfactorsforLBP.
TheconclusionsofBakkeretalhavebeencriticised(Takalaetal.2010).First,theresultsoftheincludedstudiesshouldbeconsideredas"inconsistent",not"conflicting",becausenoneofthestudiesindicatedthatthenon-exposedgroupwouldhaveahigherriskthantheexposedgroup.Second,eveninstudieswithoutstatisticallysignificantresults,trendsdidexistforanelevatedriskwithincreasedlevelsofexposure.
Fivecase-controlstudiesandfiveprospectivecohortstudieswereincludedinanotherrecentsystematicreviewonoccupationalbendingortwistingandLBP.TheconclusionwasthatthereviewedevidencewasconflictingandnotsupportiveofanyclearcausalrelationshipbetweenoccupationalbendingortwistingandLBP(Waietal.2009).However,theresultsdidsuggestthatbendingactivitiesinvolvinghigherdegreesoftrunkflexionwereassociatedwithdisablingtypesofLBPincertainworkingpopulations.
Inadditiontophysicalloadfactorsthereisalsoevidencethatpsycho-socialfactorsplayaroleintheaetiologyofLBP.Forsymptom-freepeople,thereisstrongevidencethatindividualpsychosocialfindingsareariskfac-torfortheincidence(onset)ofLBP.However,thesizeoftheeffectissmall(Waddelletal.2001).Areviewofreviewshasalsobeenpublishedontheassociationsbetweenworkplacepsychosocialfactorsandmusculoskeletalpain(Macfarlaneetal.2009).Thisreviewclaimedthatoutofthespecific
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work-relatedpsychosocialfactorsconsidered,theimportantfactorswerejobdemands,support,jobautonomyandjobsatisfaction.Withrespecttobackpain,themostconsistentconclusions(4reviewspositiveoutof6)werewithhighjobdemandsandlowjobsatisfaction.Thereviewempha-sisedtheimportanceofdevelopingstandardisedmethodsforconductingevaluationsofexistingevidence,andtheimportanceofinvestigatingnewlongitudinalstudiestoclarifythetemporalrelationshipbetweenpsycho-socialfactorsandmusculoskeletalpainintheworkplace.
Oneoftheincludedreviews(Hoogendoornetal.2000)foundalsostrongevidenceforlowsocialsupportatworkasariskfactorforLBP.However,thisresultwassensitivetochangesintheratingsystemandthemethodologicalqualityofthestudies.Theauthorsconsideredalsothattheeffectforlowjobsatisfactioncouldbeapossibleresultofinsuf-ficientadjustmentforpsychologicalworkcharacteristicsandphysicalloadatwork.Theyconcludedthatthereseemedtobeevidenceforaneffectofpsychologicalfactorsatworkbutthattheevidencefortheroleofspecificwork-relatedpsychologicalfactorshasnotbeenestablishedyet(Hoogendoornetal.2000).
PsychosocialriskfactorsseemtovaryaccordingtothetypeofLBP.InaFinnishprospectivecohortstudy(Kaila-Kangasetal.2004),lowjobcon-trolandlowsupervisorsupportatbaselinewereassociatedwithincreasedriskofhospitalisationforbackdisordersinthe17yearfollow-up.Therewasnosimilarassociationforintervertebraldiscdisorders.Instead,ithasbeenshowninanotherFinnishstudythatphysicallydemandingworkwasariskfactorforsciaticaamongmen(Kaila-Kangasetal.2009).Theriskincreasedwiththelengthoftheexposureforthefirst20years,butdecreasedthereafter.Thisstudyfoundalsoaremarkablyhighprevalenceofsciaticaamongthosewhowerenotworking.Inthisgroup,sciaticawasstronglyassociatedwithpreviousworkexposures.Theseresultsindicatethatprematurehealth-relatedselectionoutofheavyworkhadoccurred.
TheresultsofphysicalloadexposuresasriskfactorsforLBPinmostreviewshavebeenratherinsensitivetoslightchangesintheassessmentoftheoutcomesandthemethodologicalqualityofthestudies.This,however,doesnotapplytotheresultsforpsychologicalfactors.Thisindicatesthatthebodyofevidencesupportingtheroleofphysicalloadasariskfactorforbackpainissomewhatmoreconsistentthanthatforthepsychosocialfactors.
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3.1.3. Upper extremity disorders
Table2showstheknownoccupationalphysicalriskfactorsforUED.ThemostcommonlyreportedriskfactorsforUEDasagrouparerepetitivemovements,force,andhand-armvibration,whereaspsychosocialorworkorganisationalriskfactorsincludehighjobdemand,lowdecisionlatitude,lowsocialsupport,aswellasfewrestbreakopportunities(Punnettetal.2004).
Table 2. Work-related risk factors of UeD
Diagnosis Risk factors ReferencePhysical risk factors
uED in general
repetitive movements, force, and hand-arm vibration
For men: High level of physical demand, high repetitiveness of task, postures with arms at or above shoulder levels, tasks with full elbow flexion For women: Postures with extreme wrist bending and use of vibrating hand tools
(Punnett et al. 2004)
(roquelaure et al. 2009)
Epicondylitis repetitive movements of the arms and forceful activities
Handling heavy tools or loads, high hand grip forces, repetitive movements, and work with vibrating tools
(Shiri et al. 2006)
(van rijn et al. 2009a)
CTS Work tasks with vibrating tools, handgrip with high forces, repetitive movements of the hands, and prolonged work with flexed or extended wrist
(Shiri et al. 2009; van rijn et al. 2009b)
Shoulder pain
Physically strenuous work, working with trunk forward flexed or with a hand above shoulder level
Overhead work, repetitive work with shoulder, lifting, pushing or pulling
(Miranda et al. 2001)
(Walker-Bone et al. 2005)
rotator cuff tendinitis
Cumulative working with hand above shoulder level (Miranda et al. 2005)
Forearm pain repetitive tasks (Macfarlane et al. 2000)Psychosocial risk factors
uED in general
High job demand, low decision latitude, low social support, few rest break opportunities
Both high and low job demands
For men: High psychological demand For women: Low level of decision authority in women
(Punnett et al. 2004)
(Macfarlane et al. 2009)
(roquelaure et al. 2009)
Shoulder pain Mental stress
Monotonous work, high job demands and psychological distress
(Miranda et al. 2001)
(Andersen et al. 2003)
Forearm pain Poor satisfaction with level of support from colleagues/supervisor (Macfarlane et al. 2000)
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3pREVIOuSSTuDIESONMuSCuLOSKELETALDISORDERS,DISABILITYANDWORK
TheriskfactorsforUEDdifferaccordingtothespecificdiagnosis.Handlingofheavytoolsorloadsandrepetitivemovementsareassoci-atedwithlateralepicondylitis,whereasrepetitivemovements,forcefulactivitiesandworkingwithvibratingtoolsareriskfactorsformedialepicondylitis(Shirietal.2006;vanRijnetal.2009a).
Worktasksdemandinghandgripwithhighforcesortheuseofvi-bratingtoolsareassociatedwithanincreasedprevalenceofCTS(Shirietal.2009).Theassociationisstrongerifthesetaskswereaccompaniedbyrepetitivemovementsofthehandorwrist.Inaddition,prolongedworkwithaflexedorextendedwristhasbeenshowntobeariskfactorforCTS(vanRijnetal.2009b)
Consistentfindingshavebeenfoundforrepetitivemovements,vibrationanddurationofemploymentasoccupationalriskfactorsofshoulderpaininareviewwith29cross-sectionalstudies(vanderWindtetal.2000).Nearlyallstudiesthathaveassessedpsychosocialriskfac-torshavereportedatleastonepositiveassociationwithshoulderpain,buttheresultswerenotconsistentacrossstudiesforhighpsychologicaldemands,poorcontrolatwork,poorsocialsupport,orjobdissatisfaction.
Anotherreviewconcludedthatthework-relatedriskfactorsforshoulderpainareoverheadwork,repetitiveworkwiththeshoulder,andlifting,pushingorpulling(Walker-Boneetal.2005).Evidencesuggeststhatcumulativeintensiveshoulderworkparticularlyincor-poratingcombinationsofexposuresisassociatedwithasignificantlyincreasedprevalenceofshoulderdisorders.Thework-relatedfactorsaspredictorsofshoulderpaindifferaccordingtothenatureofthedisorder.Aprospectivestudyfoundthatmentalstressandphysi-callystrenuouswork,aswellasworkingwithtrunkforwardflexedorwithahandabovetheshoulderlevelincreasedincidentshoulderpain,whereaspersistentsevereshoulderpainwasassociatedwithoverloadatworkandworkingwithahandabovetheshoulderlevel(Mirandaetal.2001).
Withrespecttothepsychosocialfactors,monotonouswork,highjobdemandsandpsychologicaldistresswerethreeexposuresthathavebeenshowntoincreasetheriskofshoulderpaininaprospectivestudyamongworkersinindustrialandservicecompanies.Furthermore,poorwork-placesupportfromcolleagues/supervisorsandpsychologicalmorbidityincreasetheriskofadhesivecapsulitis(Andersenetal.2003).
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Thegenderoftheemployeealsoseemstoplayaroleinriskfac-torsofUED.InaFrenchstudywherespecificUEDwerediagnosedbytrainedOHphysicians,theriskfactorsdifferedbetweenmenandwomen(Roquelaureetal.2009).Highlevelofphysicaldemands,highrepetitivenessofthetask,postureswiththearmsatoraboveshoulderlevels,andtaskswithfullelbowflexionincreasedtheriskofUEDinmen.Inwomen,UEDwereassociatedwithpostureswithextremewristbendinganduseofvibratinghandtools.PsychosocialriskfactorswereonlymodestlyassociatedwithUED,highpsychologicaldemandsinmenandalowlevelofdecisionauthorityinwomen.Anotherstudyfoundsimilarresultsandtheauthorsconcludedthatgenderdifferencesinresponsetophysicalworkexposuresmayreflectgendersegregationinworkandpotentialdifferencesinforceproducingcapacity(Silver-steinetal.2009).
Thereisevidencethatbothindividualpsychologicalfactors(worryanddistress)andworkplacefactorscorrelatewiththeonsetofpaininUED(Shawetal.2002b).Theavailableevidencealsosuggeststhatpsy-chologicalandoccupationalpsychosocialvariableshaveanimportantroleintheaetiologyofshoulderpain.Inareviewofreviews(Macfarlaneetal.2009)thereweresixreviewsconductedonneck/shoulderandforearmpainandpsychologicalfactors(altogether85individualstudies)whichconcludedthatbothhighandlowjobdemandswereassociatedfactors.Lowjobdemandsincludedthejobbeingevaluatedasmonotonousorwithinsufficientuseofskills.
Non-specificforearmpainhasbeenshowntobeassociatedwithre-petitivetasks(Macfarlaneetal.2000).Inthesamestudy,newonsetfore-armpainwasindependentlypredictedbypsychologicaldistress,aspectsofillnessbehaviour,aswellaspsychosocialfactorssuchassatisfactionwiththelevelofsupportfromcolleagues/supervisor.Infact,non-specificshoulderpainseemstobemorehighlyrelatedtopsychosocialandin-dividualpsychologicalfactors,whereaschronicrotatorcufftendinitisisrelatedtocumulativeloadingontheshoulder,ageandinsulin-dependentdiabetesmellitus(Mirandaetal.2005;Viikari-Junturaetal.2008).
Asaconclusion,itseemsthatthemorespecificthedisorder,themoreconvincingistheevidencethatcertainphysicalloadexposuresatworkareriskfactors.Psychosocialriskfactorsseemtoplayamoresignificantpartintheaetiologyofmorenon-specificUED.Therefore,thechallenge
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inmanagingwork-relatedUEDistomakethecorrectdiagnosisinordertofindthebestwork-relatedintervention.
3.1.4. Work-related interventions in preventing musculoskeletal disorders
InterventionstudiesaimingatthepreventionofMSDusuallyincludeallavailableemployeesintheworkplaceregardlessofwhethertheyhavehadthedisorderpreviouslyornot.Consequently,it ishardlyeverpossibletodistinguishbetweenprimaryandsecondarypreventionstudies.Theinterventionisdirectedtoboththosewithorwithoutpriorsymptomsandrelateddisability,andthosewithpresentsymptoms.Thesesubgroups,however,areusuallytakenintoconsiderationinthestatisticalanalyses.
Multicomponentinterventionshaveagreaterchancethansingleinterventionsintheirsuccessinreducingwork-relatedMSDaccordingtoacomprehensivereview(Silversteinetal.2004).Modifyingindividualfactorsisnotparticularlyusefulinpreventingwork-relatedMSD,butexerciseappearstobeeffectiveinmitigatingsomeoftheconsequences.Inaddition,participatoryapproacheshavebeenoften,thoughnotal-ways,successful.
Thereviewoftheevidenceontheeffectivenessoflumbarsupports,educationandexerciseintheprimarypreventionofbackpainintheworkplacewasupdatedin2004(vanPoppeletal.2004).Accordingtofivenewpapersaddedtotheelevenpreviouslyavailabletrials,therewasstillnoevidencetosupporttheuseoflumbarsupportsoreducationinthepreventiononbackpain.Moreover,evenwhenincludingtheresultsofthenewtrials,therewasstillonlylimitedevidencetosupporttheeffectivenessofexercise.
ExerciseinterventionstopreventLBPamongemployeeshaveanef-fectonnewepisodesofLBPaccordingtoanothersystematicliteraturereviewontheeffectivenessofLBPinterventionsintheworkplace(Tveitoetal.2004).Instead,education,lumbarsupportsormultidisciplinaryinterventionsshowednosupportfortheireffectivenessinpreventingbackpain.Similarconclusionswerereachedinanotherreview(Bosetal.2006):trainingandeducationalonewerenotsufficienttoachieveanydecreaseinmusculoskeletalsymptoms,butinadditiontoergonomic
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intervention(i.e.,theuseofadditionalmechanicalorotheraidequip-ment),adecreaseofmusculoskeletalsymptomscouldbeattained.
Amixedlevelofevidencewasobservedforthegeneralquestion,whetherofficeinterventionsamongcomputerterminalusershaveanyeffectonmusculoskeletalorvisualhealth(Breweretal.2006).Thisre-viewincludednotonlyRCTs,butstudiesusingdifferentstudydesigns.Moderateevidencewasobservedfor(1)noeffectofworkstationadjust-ment,(2)noeffectofrestbreaksandexercise,and(3)positiveeffectofalternativepointingdevicesonmusculoskeletaloutcomesincomparisontoaconventionalmouse.Mixedorinsufficientevidenceofeffectwasobservedforallotherinterventions.
Thereisnoevidencetosupportthebenefitsofproductionsystems/organisationalcultureinterventions(Boococketal.2007).Thatreviewidentifiednosingle-dimensionalormulti-dimensionalstrategyforinterventionthatwasconsideredasbeingeffectiveacrossoccupationalsettings.Trialshavemainlyincludedcomputerterminalworkersandshownonlyamodesteffectofworkplaceadjustments,exerciseandad-viceasapproachesforpreventingandmanagingneck/upperextremitymusculoskeletalconditions.
Burtonetal(Burtonetal.2009)haveconcludedthateffectivein-terventionsforUEDrequireamultimodalapproachinwhichspecifictreatmentwouldbecoupledwithworkplaceaccommodation.Theyalsoemphasizedthatanintegrativeapproachbyallstakeholders(employer,workerandhealthprofessional)wasafundamentalrequirementinfacili-tatinganearlyreturntowork.Othershaveemphasizedtheimportanceofcommunicatingwithsupervisors.Theirneedsandchallengeshavetobeidentifiedinadditiontotailoringtheprogramtoaccommodateproduction,work-taskneeds,andtobeasmarginallydisruptiveaspos-sible(Feuersteinetal.2006).
Inaclusterrandomisedcontrolledtrial(Haukkaetal.2010)kitchenworkersintheinterventiongroupwereencouragedtoactivelyparticipateinworkanalysis,planning,andimplementingtheergonomicchangesaimedtodecreasephysicalandmentalworkload.Duringthefollow-up,nofavourable,evenadverse,effectsonthepsychosocialfactorsatworkwerefound.Inaddition,theseauthorshavereportedpreviouslythattherewasnoevidencefortheeffectivenessoftheinterventioninreducingtheperceivedphysicalloadorpreventingMSD(Haukkaetal.
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2008).However,asignificantlyreducedriskoffutureshoulderpainwasobservedinasubgroupofemployees,whoseworktasksperceivedasthemoststrenuouswerereduced(Pehkonenetal.2009).
TheabovementionedRCTwasincludedinthereviewontheeffec-tivenessofergonomicworkplaceinterventionsonLBPandneckpain(Driessenetal.2010).Thisreviewacceptedonlyrandomisedcontrolledtrials,whichincludedinterventionstargetedatchangingthebiomechani-calexposureattheworkplaceoronchangingtheworkorganisation.Theresultswerethatthereislowtomoderatequalityevidencethatthesekindsofinterventionsarenotanymoreeffectivethannoergonomicinterven-tiononshortandlongtermLBPandneckpainincidenceorprevalence,shortandlongtermLBPintensity,andshorttermneckpainintensity.Therewaslowqualityevidencethataphysicalergonomicintervention(forexample,armboard)wassignificantlymoreeffectiveonthereduc-tionofneckpainoverthelongtermthannoergonomicintervention.
Inconclusion,theresultsofpreviousstudiesonwork-relatedriskfactorsforMSDhavenotbeenconfirmedininterventionstudies.Thisiseitherduetothefactthatinterventionstudieshavefailedtomodifyallrelevantwork-relatedfactorsattheworkplace,orthatmusculoskeletalsymptomsanddisordersareonlypartlycausedbywork-relatedfactors,andtheotherrelevantfactorsarebeingleftoutsidethescopeoftheinterventions.
3.2. Work-related risk factors of sickness absence
3.2.1. general
PainandothersymptomscausedbyMSDcanleadtosignificantpersonaldistress,lossoffunctionanddisability.Identifyingthefactorsassociatedwithdecreasedmusculoskeletalfunctionmayleadtothedevelopmentofmoreeffectiveinterventions.Toolsforearlyidentificationofworkerswithmusculoskeletalsymptomswhoareatahighriskofprolongeddis-abilitywouldhelptofocusclinicalattentiononthepatientswhoneeditmost,whilehelpingtoreduceunnecessaryinterventions(andcosts)amongothers(Dionneetal.2005).Bytargetingspecifictreatmentandrehabilitationtopotentialhigh-riskcasesearly,onecouldarguethatit
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3pREVIOuSSTuDIESONMuSCuLOSKELETALDISORDERS,DISABILITYANDWORK
shouldbepossibletopreventadverseoutcomesincludingunnecessaryprolongationofdisability.
ClinicalpracticeguidelineshaveprovidedusefulalgorithmsforthemedicalmanagementofLBP,butthesedonotaddresscertainfactorsthatmayinfluenceLBPrelateddisability(Shawetal.2001).Basedontheevidencethatmultiplefactorscontributetodisability,interventionsthataddressmedical,workplace,andpsychosocialissuesshould,intheory,bemorelikelytoproduceimprovedoutcomesthantraditionalmedicaltreatmentalone.
Attentionhastobepaidtothefactthatagreatdealofavailableevi-denceonMSDandrelateddisabilityhasfocusedondisordersconsideredasbeingwork-related.Inmanycountriesthisentitlestheworkertofileaworker'scompensationclaimfollowedbytherighttofreemedicalcareorotherbenefits.Ithasbeenshownearlierthatwork-relatedLBPisdistinctfromsimilarnon-work-relatedconditionsinthatasuddenonsetisusu-allyreported,anddisabilityoutcomesareusuallylessfavourabledespitemoreintensivetreatments(Shawetal.2005).ThissamephenomenonislikelytoapplytootherMSDaswell,takingintoconsiderationthesignificanceoftheindividual'sownperceptionsonthedisabilityoutcome(formore,seechapter3.4.1.).
AccordingtoaFinnishstudyinvestigatingworkerspredominantlyengagedinphysicalwork(Taimelaetal.2007),self-ratedfutureworkabilityandperceivedmusculoskeletalimpairmentwerestrongdetermi-nantsofsicknessabsence.Amongthosesusceptibletotakingsickleave,theestimatedmeannumberofabsencedaysincreasedby14 %foreachincreaseofoneunitoftheimpairmentscoreonascalefromzerototen.
3.2.2. Low back pain
AccordingtotheannualstatisticsoftheFinnishSocialInsuranceInsti-tution,backpain(M40–54inInternationalClassificationofDisease)accountedfor14 %ofallcompensateddisabilitydays,and40 %ofalldisabilitydayscausedprimarilybyMSD(Kansaneläkelaitos2008).Thedirectfinancialcostsduetoback-relateddisabilitydayswas113M€totheSocialInsuranceInstitution(15 %oftotalcosts).
Table3showswork-relatedriskfactorsofsicknessabsenceduetoLBP.Thereisepidemiologicalandclinicalevidencethatcareseekingand
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backdisabilitydependmoreoncomplexindividualandwork-relatedpsychosocialfactorsthanonclinicalfeaturesorthephysicaldemandsofwork(Waddelletal.2001).
Table 3. Work-related risk factors of sickness absence due to lbP
Risk factors ReferencePhysical risk factors
Harmful biomechanical loads
Exposure at work to trunk flexion, trunk rotation and lifting
Doing heavy physical work
Heavier occupations with no modified duty
(Wickström et al. 1998)
(Hoogendoorn et al. 2002)
(Steenstra et al. 2005)
(Shaw et al. 2001)
Psychosocial risk factors
Lack of recognition and respect at work
Perceived control and low support at the workplace
Self-reported job demands
Low job satisfaction/job dissatisfaction
(Wickström et al. 1998)
(Shaw et al. 2001; Werner et al. 2009)
(Shaw et al. 2001)
(Truchon et al. 2000; Hoogendoorn et al. 2002)
Psychological risk factors
Negative beliefs about LBP, poor coping abilities
Distress (psychological distress, depressive symptoms, and depressive mood)
Pain avoidance beliefs, pain coping, psychological distress, problem solving orientation
Subjective negative appraisal of one's ability to work
(Werner et al. 2009)
(Shaw et al. 2001; Pincus et al. 2002)
(Shaw et al. 2002b)
(Truchon et al. 2000)
Other High level of disability, social isolation, receiving a high level of compensation
Delayed reporting, severity of pain and functional impact, shorter job tenure
(Steenstra et al. 2005)
(Shaw et al. 2001)
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Nocoresetofpredictorsexistsforsicknessabsenceingeneral,accord-ingtoasystematicreviewonevidenceofpredictorsforsicknessabsenceinpatientswithnon-specificLBP(Kuijeretal.2006).Thereviewstud-iedseparatelythepredictorsforabsencethreshold(i.e.,thedecisiontoreportsick)andRTWthreshold(i.e.,decisiontoreturntowork).Withrespecttotheabsencethreshold,nopredictorswerefoundforfactorspredictingsicknessabsenceatthemomentoffollow-upmeasurement,andnoconsistentevidencewasfoundfortotalnumberofsickleavedays.
Inanon-systematicreviewthedeterminantsofsicknessabsenceduetoLBPwerestudiedseparatelyforthecharacteristicsofthesick-listedworker,thecharacteristicsofthesick-listingperson(thedoctor),work-place,andtheculturalandeconomicconditionsofthesociety(Werneretal.2009).ThisevidenceshowsthatnegativebeliefsaboutLBP,co-morbidities,andpoorcopingabilitiesseemtobethemostimportantdeterminantsforclaimingsickleaveforLPB.Moreover,thedoctorwillusuallyfollowthepatient'sdemandstobegivensickleave.Theem-ployee'sperceivedsupportandcontrolattheworkplaceseemtobeofimportanceinpreventingsickleave.Nationaldifferencesineconomiccompensationforsickleaveappeartobeassociatedwithdifferencesinratesofsicknessabsence.
AccordingtotheresultsofaFinnishstudy,thetake-upofsickleaveattributedtoLBPwaspredictedbyexposuretoharmfulbiomechanicalloads(rateratio3.1).Inaddition,lackofrecognitionandrespectatworkpredictedsickleavecausedbyLBP(rateratio2.0)(Wickströmetal.1998).
Self-reportedjobdemandsappeartobebetterpredictiveofdisabilitythanmoreobjectivejobassessmentmeasures(Shawetal.2001).Workerself-reportsofgreaterphysicaldemandsofthejobappeartobepredictiveofchronicLBPdisability,whereasmoreobjectivemeasuresofphysicaldemandsarenot.Althoughworkerperceptionsofergonomicexposuremaydifferfrommoreobjectiveworkplaceassessmentstrategies,botharesubjecttoerror,butworkerreportappearstobemorestronglycorrelatedwithdisabilityoutcomes.Theauthorsconcluded,thatself-reportsmaybemoreaccurateinidentifyingunusualorhighriskdemands.However,themodestcorrelationbetweenpain,functionallimitations,andworkdisabilitysuggeststhattheseoutcomesmaydevelopsomewhatindepend-entlyfromeachotherduringtherecoveryperiodfollowingacuteLBP(Shawetal.2009a).
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Accordingtoareviewonpsychologicalfactorsaspredictorsofchronic-ity/disability,themostconsistentfindingwasthatdistress(psychologicaldistress,depressivesymptoms,anddepressivemood)isasignificantpre-dictorofunfavourableoutcome,particularlyinprimarycare(Pincusetal.2002).Thiseffectwasindependentofclinicalfactors,suchaspainandfunctionatbaseline.Inaddition,therewasmoderateevidenceforsoma-tisationhavingaroleintheprogressiontopersistentsymptomsand/ordisability,buttheeffectsizewasfoundtovary.TheauthorsconcludedthatpsychologicalfactorsplayanimportantroleinthetransitiontochronicLBP,andthattheymaycontributeatleastasmuchasclinicalfactors.
AnumberofpsychologicalvariableshavebeenshowntomediatethefunctionallimitationsofMSD,especiallychronicLBP.Thesefactorsincludepainavoidancebeliefs,paincoping,psychologicaldistress,andproblemsolvingorientation(Shawetal.2002b).
Ina3-yearprospectivecohortstudyonriskfactorsofsicknessabsenceduetoLBP(Hoogendoornetal.2002),significantrateratios,rangingfrom2.0–3.2,werefoundforexposureatworktotrunkflexion,trunkrotation,lifting,andlowjobsatisfaction.Inaddition,non-significantrateratiosofabout1.4werefoundforlowsupervisorsupportandlowco-workersupport.
Inareviewwithonlyinceptioncohortstudies(Steenstraetal.2005),thepatientswithLBPwiththehighestriskforlongtermabsencewereolderfemalescharacterisedbyradiatingpain,highlevelofdisabilityandsocialisolation,doingheavyphysicalwork,andreceivingahighlevelofcompensation.ItseemsthatinspiteoftheeffectofhistoryofLBPonrecurrencesofbackpain,ahistoryofLBPdoesnotinfluencethedura-tionofsickleaveduetoLBP.
Asystematicreviewofstudiesonthebiopsychosocialfactorspre-dictiveofnotreturningtoworkduetoLBPexamined18prospectivestudies(Truchonetal.2000).Thework-relatedpredictivefactorswereasubjectivenegativeappraisalofone'sabilitytoworkandjobdissatisfac-tion.Theimportanceofcertainpsychologicalvariables,likeattitudesandbeliefs,aswellascopingstrategies,wasalsoemerging.
Areviewofstudiesassessingthevalueofvariousprognosticfactorstopredictextendeddisabilityafteranacuteepisodeof"occupationallyattributed"LBPfoundthatsignificantprognosticfactorsincludelowworkplacesupport,personalstress,shorterjobtenure,priorepisodes,
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heavieroccupationswithnomodifiedduty,delayedreporting,severityofpainandfunctionalimpact,radicularfindings,andextremesymptomreporting(Shawetal.2001).
ItislogicalthatclinicaldataalonedoesnotpredictreliablytheriskofsicknessabsenceinLBP.Painasasubjectiveexperienceandfunctionallimitationsinrelationtoworkdemandsmaycomplicatethepossibili-tiestocontinueworking.MoreresearchisneededtocreatealternativemethodsofsupportingworkingdespitethepresenceofLBP,takingintoaccountthecumulatingevidenceofthebenefitsofstayingactiveinthemanagementofMSD.
3.2.3. Upper extremity disorders
UEDcauseremarkabledisabilityresultinginlostproductivity.Forexample,inWashingtonStatein1990–1998,theaveragetimelostfromworkwas170–251dayspercompensationclaimrelatedtoUED(Silversteinetal.2002).
Across-sectionalstudywasperformedamongworkersrepresentingavarietyofoccupationsbutsharingacommonworkers'compensationandemployeehealthbenefitprogram(Shawetal.2002b).Theresultsshowedthatfactorsotherthanpainexplainedtwiceasmuchvariabilityinupperextremityfunctionallimitationasexplainedbypainalone.Thissuggeststhatfunctionallimitationmaypersistsomewhatindependentlyofpainamelioration.Aftercontrollingforpainandgenderinamultipleregressionanalysis,thefactorscontributingtofunctionallimitationwerenon-painrelatedupperextremitysymptoms(forexample,sleepdistur-bance,numbness,tingling),symptomsinbothhands,feelingsofbeingoverwhelmedbypain,lowconfidenceinproblemsolvingabilities,andhigherergonomicriskfactorexposuresatwork.
3.2.4. Prevention of sickness absence caused by musculoskeletal disorders
Thischapterevaluatesinterventionsaimingatreducingthefrequencyofmusculoskeletalsicknessabsence(totalnumberofspells/allemployees)orthelengthofmusculoskeletalsicknessabsence(sick-leavedays/sick-listedpersons).
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Thetreatmentchosenbythephysicianiscrucialfortherecoveryprocess.Acontrolledtrialshowedthataslittleastwodaysofbedrestinstructedbythephysicianleadtoaslowerrecoverythantheavoidanceofbedrest,aswellastolongersickleaves(Malmivaaraetal.1995).ThisstudyofworkerswithacuteLBPsuggeststhatavoidingbedrestandmaintainingordinaryactivityleadtothemostrapidrecovery.
Screeningformedical"redflags"anddiagnostictriageisimportantintheexclusionofseriousspinaldiseasesandnerverootproblems(Waddelletal.2001).Sinceindividualandwork-relatedpsychosocialfactorsplayanimportantroleinthepersistenceofsymptomsanddis-ability,screeningfor"yellowflags"canhelptoidentifythoseworkerswithLBPwhoareatriskofdevelopingchronicpainanddisability.Laterthesystemof"yellowflags"wasrefinedandworkplacefactorswerecategorisedeitheras"blackflags"includingactualworkplaceconditionsthatcanaffectdisability,or"blueflags"includingindividualperceptionsaboutwork,whetheraccurateorinaccurate,thatcanaffectdisability(Shawetal.2009b).
Blueflagshavebeenconceptualisedasworkerperceptionsofastress-ful,unsupportive,unfulfilling,orhighlydemandingworkenvironment.Blackflagsincludebothemployerandinsurancesystemcharacteristicsaswellasobjectivemeasuresofphysicaldemandsandjobcharacteristics(Shawetal.2009b).Ithasbeenclaimedthatabetterunderstandingofthemeaning(thoughts,beliefsandattitudes)thatpatientsattributetotheirpaincouldbeacriticalsteptowardimprovingreturntoworkoutcomes(Loiseletal.2005).
Althoughworkingconditionswithuncomfortableworkingposi-tions,liftingorcarryingloads,pushingandpullingloadsaswellastheuseofvibratingtools,haveallbeenfoundtobeassociatedwithsicknessabsence,ithasbeenstatedthatmanyyearsofimplementingergonomicadaptationshavenotreducedtheincidenceofsicknessabsence(Werneretal.2009).
ACochranereview(vanOostrometal.2009)hasbeenpublishedfocusingstrictlyonrandomisedcontrolledtrials.Theresultsshowedthatwhencomparedtousualcare,thereismoderate-qualityevidencetosupporttheuseofworkplaceinterventionscarriedoutclosetotheworkplaceandincollaborationwiththekeystakeholdersinordertopreventworkdisabilityandreducesicknessabsenceamongworkers
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withMSD.Noevidencewasfoundforthebenefitsofworkplacein-terventionsonhealthoutcomes(forexample,painorfunctionalsta-tus).ThiswasconsideredassupportforthehypothesisthatRTWandresolutionofsymptomsarenotequivalent.Inotherwords,workplaceinterventionstendtoaddresstheworkdisabilityproblemandnottheunderlyingmedicalproblem.
Thesupervisors'roleinthemanagementofmusculoskeletalpainhasbeenevaluatedinacontrolledcasestudy(Shawetal.2006).Elevensupervisorsinaninterventiongroupand12supervisorsinadelayedinterventioncontrolgroupfromthesameplantwereprovidedwithtwo2-hourtrainingworkshopsseparatedby4to7days.Thefundamentalmessageintheworkshopswasthatsupportive,proactive,andcollabora-tivecommunicationswithemployeesaboutergonomicriskfactorsandmusculoskeletalpainanddiscomfortwouldbelikelytoreducedisabilitycostsandimproveemployeemorale,productivityandretention.Work-ers'compensationclaimsdatainthesevenmonthsbeforeandaftertheinterventionshoweda47 %reductioninnewclaimsandan18 %reductioninactivelost-timeclaimsversus27 %and7 %,respectively,inthecontrolgroup.Accordingtothatstudy,improvingtheresponseoffrontlinesupervisorstoemployees'work-relatedhealthandsafetyconcernscouldachievesustainablereductionsininjuryclaimsanddis-abilitycosts.
Basedoninterviewswith30employeesShawetal.(2003b)devel-oped11commonthemesfortheroleofsupervisorstopreventwork-placedisabilityafterinjury:accommodationtoreduceergonomicrisksordiscomfort,communicatingwithworkers,responsiveness,concernforwelfare,empathy/support,effortstounderstandtheemployee'ssituation,fairness/respect,follow-up,shareddecisionmaking,coor-dinatingwithmedicalproviders,andobtainingco-workersupportofaccommodation.
Severalstudiesperformedindifferentcountrieshaveshownamis-matchbetweenpublicbeliefsaboutbackpainandcurrentscientificevidence(Buchbinderetal.2008).Sincebeliefsandattitudesaboutbackpainareassociatedwiththedevelopmentofchronicity,itisapparentthatstrategiesareneededthatalignpublicviewswithcurrentevidence.MediacampaignsinScotlandandNorwayhighlightingtheawarenessofstayingactivethroughanepisodeofLBPdidnotchangesickness
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behaviourdespiteimprovedbeliefsinthegeneralpublic.However,anearliercampaigninAustraliawasfollowedbyacleardeclineinthenumberofclaimsforbackpain,ratesofcompensateddaysandcostsofmedicalcare.ThepossibleexplanationforthisisthatonlyinAustraliawerespecificadvertisementsaimedatemployersshowingthebenefitsofreintegratingemployees,theimportanceofmodifiedwork,andthepenaltiesinvolvedfornoncompliance(monetaryfines).
InNorway,inadditiontoamediacampaignaimingatimprovingbeliefsaboutLBPinthegeneralpublic,aprojecttrainedpeeradvisersinsixparticipatingworkplaces(Werneretal.2007).Thetaskofthispeeradviserwastoprovideinformationaimedatreducingfearofthepain,supportiveadvice,andarrangingformodificationsofworkloadsforalimitedperiodoftime.Eventhoughtheprevalenceofbackpainremainedconstantthroughoutthestudyperiod(threeyears),thecombinationofpeersupportgivenbyatrainedforeman,unionleaderorpersonnelofficerandmodifiedworkloadseemedtohavesupplementaleffectstoageneralmediacampaigninreducingsicknessabsenceduetoLBPandimprovementsinbeliefsaboutbackpain.
3.3. Work-related determinants of sickness presenteeism
Intherecentpast,theworker'sabilityorcapacitytoproducegoodsordeliverserviceswhilesufferingfromMSDhasbeenofparticularinterestintheareaofoccupationalresearch.Escorpizohasproposedthatworkproductivitywithinthecontextofwork-relatedMSDisdeterminedbythehealthconditionitself,thecapacity,desireanddifficultyofworking,aswellaswork-lifebalanceandnon-occupationalfactors(Escorpizo2008).Themeasurementofworkproductivityiscrucialtoinitiating,evaluating,andmonitoringdisabilitymanagement,forexample,em-ployeewellnessandergonomicprograms,andclinicalinterventionsinthemanagementofMSD.
InaFinnishpostalsurveyoflabourunionmembers(Böckermanetal.2009),presenteeism("presentatworkinspiteofsickness")wasassociatedwithpermanentfull-timework,shiftorperiodwork,regularovertime,overlongweeklyworkingtime,andefficiencyrequirements
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atwork.Ontheotherhand,lowerlevelsofpresenteeismwereassoci-atedwiththepossibilityofreplacementbyasubstitute,matchbetweendesiredandactualworkinghours,andthepossibilityoftakingashortsickleavewithouttheneedforsicknesscertificate.
Accordingtoasystematicreviewonemployeehealthandpresenteeism(Schultzetal.2007a),thestudiesintheliteraturefocusingonMSDaresurprisinglyrare.Mostoftheearlierstudieshaveassessedproductivitylossrelatedtoself-reportedsymptoms,whereasthereisaverylimitednumberofstudiesonproductivitylossassociatedwithclinicallydiag-nosedMSD.Thenatureofthemusculoskeletalconditionpresumablyaffectsproductivity,andtheriskfactorsforproductivitylossrelatedtovariousdisordersmayvary.Littleisknownoftheeffectsofthemuscu-loskeletaldiagnosesonproductivityloss.
SomeNorth-AmericansurveysonpresenteeismhavenotfocusedonlyonMSDbutalsoonotherhealthconditions.Amongworkersparticipatinginatelephonesurveymeasuringbothabsenteeismandreducedperformanceduetocommonpainconditions,thosereport-ingbackpainhadaveragelostproductivetimeof5.2hoursperweek(Stewartetal.2003).Themajority(77 %)ofthelostproductivityduetoanypainconditionwasexplainedbyreducedperformancewhileatworkandnotbyworkabsence.Inanothersurvey(Loeppkeetal.2007),backorneckpainwasthetopmedicalconditionaccountingforannualmedical,drug,andproductivitylosscostsper1000fulltimeemployeesinalltypesofcompanies.
Table4liststheknownwork-relateddeterminantsofsicknesspresen-teeismduetoMSD.Poorhealthhasbeenproposedtobeaprerequisiteforsicknesspresenteeism.Inaddition,severalotherfactorsrelatedtoworkandpersonalcircumstanceshavealsobeenassociatedwithpresenteeism,suchaslowreplaceabilityorhighattendancerequirements,forexample,havingtocompensateforallworknotdoneafteraperiodofabsence,lackofworkresources,timepressure,jobstress,jobinsecurity,andlongworkhours(Bergströmetal.2009).Personalfactors,despitehavingasomewhatweakerrelationtopresenteeismthanworkfactors,includedfinancialproblems,lackofindividualboundaries,over-commitmenttowork,conservativeattitudestowardsicknessabsence,ageandlimitededucation(Bergströmetal.2009).
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Table 4. Work-related determinants of sickness presenteeism
Determinants Reference
Individual factors
Poor health, financial problems, conservative attitudes toward sickness absence, age, limited education
Worse physical health, more functional disability
Musculoskeletal complaints, worse physical, mental and general health, recent absenteeism
Physical exercise fewer than 8 times during the last month
(Bergström et al. 2009)
(Lötters et al. 2005)
(Meerding et al. 2005)
(Hagberg et al. 2002)
Work-related factors
Permanent full-time work, shift or period work, regular overtime, overlong weekly working time, and efficiency requirements at work
Low replaceability or high attendance requirements at work for example, having to compensate for all work after a period of absence, lack of work resources, time pressure, job insecurity, and long work hours
Working overtime, computer mouse use for more than 0.5 h/day
(Böckerman et al. 2009)
(Bergström et al. 2009)
(Hagberg et al. 2002)
Psychosocial and psychological factors
Job stress, lack of individual boundaries, over-commitment to work
Poorer relations with the supervisor
Job demands
(Bergström et al. 2009)
(Lötters et al. 2005)
(Hagberg et al. 2002)
Reducedproductivityafter2-to6-weeksicknessabsenceduetoMSDwasquantifiedinaprospectivecohortstudyusingself-admin-isteredquestionnaires(Löttersetal.2005).Reducedproductivitywasprevalentfor60 %oftheworkersaftertheyreturnedtowork,andfor40 %stillatthe12-monthfollow-up.Worsephysicalhealth,
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morefunctionaldisabilityandpoorerrelationswiththesupervisorwereassociatedwithproductivitylossshortlyafterreturntowork.Recurrentsickleavewasthegreatestpredictorofproductivitylossatthefollow-up.
Twoquestionnairesonproductivityloss("HealthandLaborQues-tionnaire"and"QuantityandQuality")werecomparedamongtwopopulationsdoingjobswithhighphysicaleffort(Meerdingetal.2005).Abouthalfoftheworkerswithhealthproblemsonthelastworkingdayreportedreducedworkproductivity.Thiswassignificantlyassociatedwithmusculoskeletalcomplaints,worsephysical,mentalandgeneralhealth,andrecentabsenteeism.Self-reportedproductivityusingaQuantityandQuality(QQ)instrumentcorrelatedsignificantlywithobjectiveworkoutput.
InaSwedishstudy(Hagbergetal.2002)amongwhite-collarcom-puterusers8 %ofallemployeesreportedreducedproductivityduetomusculoskeletalsymptoms.Themeanmagnitudeofreductionwas15 %forwomenand13 %formen.Workingovertimeandjobdemandswereriskfactorsforself-reportedreducedproductivityduetoneckandbacksymptoms,whereasphysicalexercisefewerthan8timesduringthelastmonthwasariskfactorforproductivitylossduetoneck,shoulderandupperlimbpain(Hagbergetal.2007).Inaddition,computermouseuseformorethan0.5h/daywasariskfactorforreducedproductivityowingtoshoulderandupperlimbsymptoms.
Inastudyof654computerworkerswithneck/shoulderorhand/armsymptoms(vandenHeuveletal.2007),productivitylosswasin-volvedin26 %,andmoreoften(36 %)incasesreportingbothneck/shoulderandhand/armsymptoms.Mostoftheproductivitylossinthearm/handcaseswasduepresenteeismandsicknessabsenteeismwaspresentinonly11 %ofthecases.Overallproductivitylosswasassociatedwithpainintensity,higheffortregardlessoftherewardlevel,andlowjobsatisfaction.
Inaone-yearfollow-upstudyamong771youngadultswhoreportedneckorupperextremitysymptoms,butnoproductivitylossatbaseline,theriskfactorsofproductivitylossweresymptomsinseverallocations,longerpersistenceofsymptoms,andcomputerterminaluseof8–14hours/weekduringleisuretime(Boströmetal.2008).Astrongerrela-tionshipwasfoundifthreeorfourriskfactorswerepresent.
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Inaddition,severalstudieshavefound,somewhatunexpectedly,thattheyoungeremployeesreportmorehealth-relatedproductivitylossthanolderemployees(Hagbergetal.2002;Collinsetal.2005;Alaviniaetal.2009).
3.3.1. Prevention of sickness presenteeism associated with musculoskeletal disorders
InaDutchstudy(vandenHeuveletal.2003),workerswithcomplaintsintheneckorupperlimbwererandomizedintoacontrolgroup,oneinterventiongroupencouragedtotakeextrabreaks,andanotherinter-ventiongroupencouragedtoperformexercisesduringtheextrabreaks.Afteran8-weekperiod,thesubjectsintheinterventiongroupwithbreaksonlyshowedhigherproductivity(morekeystrokes)thanthecontrolgroup.Thestrokeaccuracyrateinbothinterventiongroupswashigherthaninthecontrolgroup.However,therewerenosignificantdifferencesbetweenthethreegroupsinthereportedseverityorfrequencyofthecomplaintsbeforeandaftertheintervention.
Inanotherstudy(Rempeletal.2006),agroupofcomputertermi-nalworkersintheUnitedStateswasrandomisedtoreceiveergonomicstrainingonly,trainingplusatrackballorforearmsupport,ortrainingandbothatrackballandaforearmsupport.Despitethefactthattheforearmsupportcombinedwithergonomictrainingseemedtopreventupperbodymusculoskeletalsymptoms,therewerenosignificantdiffer-encesbetweentheinterventiongroupsineitherthecompanytrackedproductivitymeasuresorinself-assessedproductivity.
Cost-effectivenessofanactive implementationstrategyfortheDutchphysiotherapyguidelineforLBPhasbeenstudiedinaRCTincludingalsoproductivitycostsasanoutcomemeasure(Hoeijenbosetal.2005).Abouthalfofthepatientsatbaselinereportedproduc-tivitylossduetoLBPcorrespondingtoalmost2hoursonaverageperday.Comparedtobaseline,significantlymorepatientswereseenwithoutanyproductivitylossinboththeinterventionandcontrolgroupafter6(56 %and64 %,respectively)and12weeks(71 %inbothgroups).Thedifferencesbetweenthetwogroups,however,werenotstatisticallysignificant.
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3.4. Determinants of return to work
TheprimarygoalsofemployeerehabilitationandRTWprogramsmayappeartobethepayer'sinterestinreducingdisabilitycosts,butthereareadditionalincentives:humanrightslegislationinmanycountriesprohibitsdiscriminationinemploymentpracticesonthebasisofdis-abilitystatus(Brookeretal.2001).
AccordingtoasystematicreviewofthequantitativeliteratureonworkplacebasedRTWinterventions,thereisstrongevidencethatworkdisabilitydurationissignificantlyreducedbyworkaccommodationoffersandcontactbetweenhealthcareproviderandtheworkplace(Francheetal.2005).Moderateevidencewasfoundthatdisabilitydurationisalsoreducedbyinterventionswhichincludeearlycontactwiththeworkerbytheworkplace,ergonomicworksitevisits,andthepresenceofaRTWcoordinator.Thus,forthesefiveinterventioncomponents,therewasmoderateevidencethattheyreducecostsassociatedwithworkdisabilitydurationbuttherewasinsufficientorlimitedevidenceforthesustain-abilityoftheseeffects.
Aconsensuspanelof33researchersandstakeholdersselectedkeyfactorsinbackdisabilitypreventionfollowingaliteraturesearchontheassessmentofwhichfactorsthatpredictordeterminedisability(Guzmanetal.2007).ExistingresearchevidencehadlargelyfocusedonRTW.Amongthefactorswithahighimpactonoccupationalparticipationwerecareproviderreassurance(strongconsensus),expectationofrecoveryanddecreasedfears(moderateconsensus),andincreasedknowledgeoftheindividualwithbackpainandappropriatemedicalcare(lowconsensus).Ontheotherhand,therewasmajordisagreementastotheimpactofincreasedjobsatisfaction,decreasedpain,increasedfitness,improvedfunction,improvedworkstationdesign,decreasedphysicalworkload,andliftingdevices.
ManyoftheRTWstudieshavebeencarriedoutinNorthAmericawiththesettingbeingaworker’scompensationsystem.Therefore,ithasbeenclaimedthatthereisaneedforcomparativedatafromotherjuris-dictionswithdifferentinsuranceschemesandsocialpolicyframeworksincorporatingalternativelegislativeimperativesandeconomicincentives(Brookeretal.2001).Thisinformationcouldclarifytherelationship
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betweensocietalfactorsandtheavailabilityandqualityofworkplace-basedRTWprograms.
ThebarriersofrecoveryandRTWwereinvestigatedamongemployeeswithwork-relatedUED(Shawetal.2003a).Casemanagersidentifiedupto21barrierspercasewithinfivedomains:signsandsymptoms(36 %ofallbarriers),workenvironment(27 %),medicalcare(13 %),functionallimitations(12 %),andcopingoftheemployee(12 %).
Ina2-yearprospectivecohortstudyamongpatientswithbackpaininprimarycaresettings,theoutcomemeasurewas"RTWingoodhealth"at2yearscombiningpatient'soccupationalstatus,functionallimitationsandrecurrencesofworkabsence(Dionneetal.2005).Thebestpredictivemodelincludedsevenbaselinevariables,suchasthepa-tient'srecoveryexpectations,previousbacksurgery,painintensity,anddifficultyinsleeping.Thismodelwasparticularlyefficientatidentifyingthosepatientswithnowork-relatedfunctionalproblems.
3.4.1. Worker perceptions and expectations
Asystematicreview(Kuijeretal.2006)gatheredevidenceforpredictorsofthedecisiontoreturntowork("RTWthreshold").Consistentevidencewasfoundforownexpectationsofrecoveryinthatpatientswithhigherexpectationsofrecoveryhadlesssicknessabsencedaysatthemomentoffollow-upmeasurement.
TheimportanceofpsychosocialfactorsonRTWwasstudiedinasystematicreview(Ilesetal.2008)whichevaluated24studies.Thesestudiesproducedstrongevidencethatrecoveryexpectationandmoderateevidencethatfear-avoidancebeliefswouldbepredictiveofworkoutcomeinnon-chronic,non-specificLBP.Workers'ownbeliefsthattheirLBPwascausedbyworkandtheirownexpectationsabouttheirinabilitytoreturntoworkwereclaimedtobeparticularlyimportant(Waddelletal.2001).
Non-medicalfactors,especiallythoserelatedtoworkplaceconcerns,perceptionsofinjuryseverity,andexpectationsforrecovery,wereassoci-atedwithbackdisabilitydurationinaninceptioncohortstudy(Shawetal.2005).Patients(183female,385male)sufferingarecentonsetLBPcompletedaquestionnaire,andaftertheinitialvisittheclinicianscom-pletedanadditionalquestionnaire.Functionallimitationandworkstatuswereassessedonemonthafterthepainonset.Accordingtotheresultsof
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thatstudy,psychosocialfactorsseemedtomoderatethedisablingeffectsofpain,evenwithinthefirstweeksafterpainonset.Accordingtotheavailableevidence,subjectiveinterpretationsandappraisalsofpatientswouldbemorepowerfulpredictorsofpostbackinjuryrecoverythanphysicalexaminationvariables(Shawetal.2005).
Individuals'subjectiveperceptionsofpersonalandenvironmentalissuesinfluenceRTW.Itwasstatedthatthepersonalmeaningofdisabil-ityandRTWrelevancywouldbetwokeyconstructsinunderstandingRTWfromtheindividual'sperspective(Shawetal.2002a).Throughouttheexperienceofbecomingbetterandreturningtowork,theworkersassessedtheimpactofpersonalandexternalfactorsthatcontributedtotheirworkdisability.Theyalsoevaluatedtheirperformancecapabilities,andexaminedtheimportanceofworkandtheconsequencesofworkdisabilitywithintheirlifecircumstances.
Basedontheoriesoffearandavoidancebehaviour,Waddelletal.pos-tulatedthatpatients'beliefsabouthowphysicalactivityandworkaffecttheirLBParestronglyrelatedtosicknessabsenceduetoLBP(Waddelletal.1993).Inamorerecentlongitudinalstudythebeliefsaboutbackpainwerestudiedinrelationtorecoveryrateover52consecutiveweeks(Elferingetal.2009).Higherlevelsofwork-relatedfear-avoidancebeliefs(i.e.,beliefsregardingtheinevitableconsequencesofLBPinthefuture)predictedgreaterweeklyLBPandimpairment.Fasterrecoveryandpainreliefovertimewereseeninthosewhoreportedlesswork-relatedfearavoidanceandfewernegativebackbeliefs.
Inastudyofpatientswithoperativelytreatedhanddisordersorinjuries(Opsteeghetal.2009),threefactors,i.e.higherpainintensity,accidentattributedtoworkandsymptomsofpost-traumaticstress,werethemostimportantdeterminantsofdelayedRTW.Inanotherprospec-tivecohortstudy(Baldwinetal.2007),baselinephysicalfunctioningandoverallmentalandphysicalhealthstatusweremorepredictiveofspecificpatternsofpost-injuryemploymentthanpainintensitymeasures.
3.4.2. Work environment and work organisation
PsychosocialandphysicalworkenvironmentriskfactorswereexaminedaspredictorsofRTWinaDanishprospectivestudy(Labriolaetal.2006).Contrarytopreviousstudies,nosignificantassociationwasfound
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betweenworkplacesizeandthethreeRTWoutcomes(RTWwithinfourweeks/oneyearoftheonsetofsicknessabsenceanddurationofsicknessabsence).Lowmeaningofwork,stoopingortwistingtheback,liftingheavyloadsandrepetitivejobtaskssignificantlydecreasedthechanceofRTWwithinfourweeksoftheonsetofsicknessabsence.ThechanceofRTWafteroneyearofsicknessabsencewasdecreasedbybeingexposedtoastoopedworkpositionandhavingtodorepetitivejobtasks.Thedurationofsicknessabsencewasprolongedbylowskilldiscretion,lowmeaningofwork,liftingheavyloadsatwork,andpushingandpulling.
ModifieddutyandworkplaceaccommodationshavebeenshowntopreventprolongedworkabsencesforworkerswithMSDbydecreasingexposuretonormalworkdemandsaftermedicalevaluationandtreat-ment.Thiswasthemainfindingofareviewonthebasisof13highqualitystudies(Krauseetal.1998).Injuredworkerswhowereofferedmodifiedworkreturnedtoworkabouttwiceasoftenasthosewhowerenotgiventhisoption.
Alaterreportstrengthenedtheevidencethatworkplaceoffersofarrangementstohelptheworkerreturntoworkareassociatedwithreducedcompensationbenefitduration(Brookeretal.2001).Theaccommodationcouldbeachievedinseveralways,i.e.modifiedoralternatetasks,gradedworkexposure,worktrials,workstationredesign,activityrestrictions,reducedhours,orothereffortstotemporarilyreducephysicalworkdemands.Akeyconcernfromtheworker'sperspectiveisthatmodifiedworkarrangementsprovideasafeworkplaceenvironmentthatfacilitatesrecoveryfrominjuryratherthanexacerbatingit.Itwasreportedthatanyinterventionthatreducesabsencefromregularworkwaslikelytoreducelong-termchronicity,withallofitspersonalandfinancialcosts(Loiseletal.1997).
TheroleofasupervisorisvitalforthesuccessfulRTWofanemployee.Accordingtotheexistingevidence,theinterpersonalaspectsofsupervi-sionmaybeasimportantasphysicalworkaccommodationtofacilitateRTWafterinjury(Shawetal.2003b).Asystematicreviewofthequalita-tiveliteratureonreturntoworkafterinjuryhasbeenpublishedinordertobetterunderstandthedimensions,processes,andpracticesofRTW(MacEachenetal.2006).Thatreviewnotedtherelevanceofrecognisingthecomplexitiesrelatedtobeliefs,rolesandperceptionsofthemanyplayers.Goodwillandtrustwerethecrucialconditionsthatwerecentral
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tosuccessfulRTWarrangements.Inaddition,itwasobservedthatthereareoftensocialandcommunicationbarrierstoRTWandintermediaryplayershavethepotentialtoplayakeyroleinfacilitatingtheprocess.
Ithasbeenclaimedthatthemosteffectiveapproachestodisabilitypreventionarethosethatmaintainanopenandeffectivecommunica-tionamongworkers,physicians,andemployersinordertofacilitateasmoothandbroadlysupportedreintegrationintotheworkplace(Shawetal.2005).Thus,employerswhoprovideasupportiveandaccommodat-ingapproachtodisabilitymanagementmaynotbeabletoonlyreducedisabilitycostsbutalsoimproveworkerperceptionsoftheirfunctionalhealthaftertheinjury.
Inastudyofcasemanagementserviceforwork-relatedUED(Shawetal.2004),thetypesofaccommodationsobtainedbycasemanag-ersappearedtoberelativelyinexpensiveandincludedafullrangeofenvironmental,equipment,andadministrativechanges.Theseaccom-modationswereconsistentwithreducingupperextremitypain,eitherdirectlybyaddressingworkstationdesign(forexample,keyboard,deskedges)orindirectlybyalteringtheworkprocess(forexample,breaks,jobrotation).Inanotherreportfromthesamestudy(Lincolnetal.2002),theaccommodationswereclassifiedintothefollowingeightgeneralcategories:administrative,computer-related,furnishing,workstationlayout,environmental,accessories,lifting/carryingaids,andpersonalprotectiveequipment.
Beingcontactedbysomeonefromtheworkplacewasnotassociatedwithareductionintimereceivingcompensationbenefits(Brookeretal.2001).Itislikelythatmerelycontactingtheworkerintheabsenceofotherinterventionsisnotassociatedwithafasterreturntowork.Al-ternatively,perhapsthenatureofthecontactthatoccurredduringthestudywasnotconducivetofacilitatingafasterreturntowork.Althoughworkerswhowereofferedmodifiedworktendedtoreceivecompensationbenefitsforashortertime,theydidnotseemtohavereducedpainscores(Brookeretal.2001).Infact,asmallminorityofworkersexperiencedsubstantiallymorepainthanexpectedwhentheyresumedtheirwork.Theauthorsofthatreportrecommendedthatworkerandworkplaceas-sessmentsbeforeandafterthereturnoftheworkertoworkmayhelptoensurethatemployeesarenotreturnedtoworktooearlyortoworkplacesituationsthatreactivatetheirpain.
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3.4.3. Role of the medical provider
TreatmentstudiesonacuteLBPhavereportedone-monthRTWratesfrom70to90 %dependingonrecruitmentproceduresandinitialriskfactors.Thisratehasshownremarkableconsistencydespitejurisdictionaldifferencesinemploymentanddisabilitybenefits(Shawetal.2005).AhighrateofRTWshouldnotbeinterpretedasacompleteresolutionofpain,sincemostemployeescontinuesufferingfrompainandrelatedproductivitylossatwork(Shawetal.2009a).
Accordingtotheresultsofaliteraturereview(Hlobiletal.2005),theoptimalRTWinterventionforsubacuteLBPmightbeamixtureofexercise,education,behaviouraltreatment,andergonomicmeasures,butitwasnotclearwhichcomponent,orwhichcombinationofcom-ponents,wasthemosteffective.ThesamereviewconcludedthatRTWinterventionsusedintheearlier,acutephaseofLBPdidnotappeartobeeffectivewithrespecttoabsencefromwork.Thismaybebecauseofthefavourable,self-limitingcourseofLBPandabsencefromworkdur-ingthisacutephase.
Apopulation-basedRCTonbackpainmanagement(Loiseletal.1997)concludedthatchangestojobsandworkstationsusingpartici-patoryergonomicapproachwerepreferabletoworker-focusedstrate-giessuchasworkhardening(alternatingdaysattheoriginaljobwithprogressivelyincreasedtasksanddaysreceivingfunctionaltherapy).Inthatstudy,anintegratedclinical-occupationalmodelofmanagementofbackpainwastwotimesmoreeffectiveinincreasingtherateofreturntoregularworkthantheusualmedicalcare.
ThereisalsomoderateevidencethatthepresenceofaRTWcoordi-natorwouldbeassociatedwithasignificantreductionofworkdisabilityduration(Francheetal.2005).SixpreliminarycompetencydomainsofRTWcoordinatoractivitieshavebeenidentified(Shawetal.2008):(1)ergonomicandworkplaceassessment;(2)clinicalinterviewing;(3)socialproblemsolving;(4)workplacemediation;(5)knowledgeofbusinessandlegalissues;and(6)knowledgeofmedicalconditions.
Professionalcasemanagersmaybethesolutiontomanyofthecom-municationproblemsinvolvedindisabilitymanagement.Theseindi-vidualscouldidentifybarrierstoRTW,restorenormalcommunicationbetweenemployerandemployees,andengagethemedicalproviderinthis
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process(Pranskyetal.2004).Thenursecasemanagermaysuccessfullylegitimisethepatient’sviewpointandthusinitiateabidirectionaldialogueaboutRTWdirectlywiththeemployer.Thus,itwasclaimedthatitwasthisrestorationofcommunicationmorethananyotherinterventionthatmayhaveaccountedforthesuccessesofthismodel.However,aspatientsarenotaccustomedtocommunicatetheirconcerns,preferences,andexpectations,patienttrainingwouldbedesirabletoachievefullyeffectivebidirectionalinterchange(Pranskyetal.2004).
ParticipatoryergonomicshasbeenseenasonepromisingapproachtorehabilitationofworkerssufferingfromMSD.Loiseletal.havedescribedaprogramwithfoursteps(Loiseletal.2001):First,theergonomistmeetstheworkertocollectdataonpersonalcharacteristics.Jobdescriptionsaresoughtfromboththeworkerandhis/hersupervisor.Secondly,ameet-ingisorganisedintheworkplacewiththeworkerandthesupervisortocomparethejobdescriptions,makealistoftheriskfactorsforbackpain,andtoidentifyworkorganisationandjobdemandsrelevanttothebackpain.Thirdly,theergonomistvisitstheworkplacetoobservetheworktasksperformedbyanotherworker.Finally,theparticipatoryworkgroupmeetstoidentifyimprovementsintheworktasks.Finalacceptanceofthesesolutionsistheemployer'sresponsibility.
ErgonomicjobmodificationasacomponentofaRTWrehabilita-tionprogramisgenerallybelievedtohavepositiveeffectswithworkershavingsicknessabsenceduetobackpain(Silversteinetal.2004).Ithasbeenshown,however,thatdoctor-patientcommunicationsabouttheworkplaceandRTWareimportant,butnotsufficientintheabsenceofergonomicandorganisationalchangesintheworkplace(Dasingeretal.2001;vanDuijnetal.2005).Therefore,RTWcoordinatorsaspartofhealthserviceshavebeenclaimedtorepresentaneffectivestrategyforpromotingRTW.Accordingtoaliteraturereview(Shawetal.2008),theprincipalactivitiesofRTWcoordinationinvolveworkplaceassess-ment,planningfortransitionalduty,andfacilitatingcommunicationandagreementamongstakeholders.
InordertopromoterecoveryandearlyRTW,part-timesicknessabsenceispossibleinsomecountries(forexample,Finland,Sweden,Norway,andDenmark).However,theeffectivenessofpart-timesickleavehasbeenpoorlystudied(Kaustoetal.2008).ANorwegiancluster-randomisedstudyon"activesickleave"(returntoadjustedworksup-
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portedbysocialsecurityafterconventionalsickleavehadlasted16daysormore)showednobeneficialeffects,partlybecausethepart-timesickleavesystemwassoseldomused(Scheeletal.2002).
Almostallindividualstakingpart-timesickleavedoseemtobecon-tentwiththisarrangement;92 %ofemployeesonpart-timesickleaveinaSwedishsurveyexpressedsatisfaction(Sieurinetal.2007).Two–thirdsofthoseonfull-timesickleaveconsideredpart-timesickleaveasapotentiallygoodalternativeforthem.However,somedisadvantageshavealsobeendetected:aSwedishstudywithafollow-upof1.5yearsfoundthatpart-timesickleavestendedtolastlongerthanconventionalsickleaves(Eklundetal.2004).
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4. CONCEPTUAL fRAMEWORK Of ThE STUDY
Theconceptualframeworkforthestudyispresentedinfigure4.Ahealthyemployeemightdevelopsymptomsordisordersduringem-ployment(stepA).Inacaseofsymptomdevelopment,theconditioneitherallowstheemployeetocontinueworkingoralternativelytheemployeemaybeabsentfromwork(stepB).Whileatworkwiththedisorder,theemployeemayhavefullcapacitytoperformworkdutiesorhe/shemightexperienceimpairedfunctioningtosuchadegreethatproductivityatworkisreduced(stepC).Thosewhobecomesick-listedeitherreturntoworkortheirdisabilitybecomesprolonged,evenpermanent(stepD).ThisthesisaimstostudythesefourstepsusingMSDasanexample.
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4CONCEpTuALfRAMEWORKOfTHESTuDY
STEP B
STEP A STEP C
Healthyemployee
No symptoms or MSD
At workNormal
productivity
reduced productivity
Symptoms or/and MSD
On sick leave
return to work
Prolonged or permanent disability
rCT on effects of part-versus full-time sick leave on
rTW?
(Study V)
Productivity loss due to uED and effects of a workplace intervention?
(Studies iii, iV)
impact of disease and workplace
characteristics on work ability?
(Study ii)
Prevention of LBP caused by
exposure to lifting at work?
(Study i)
Primary prevention
Secondary prevention
Tertiary prevention
STEP D
FigurE 4. Theoretical framework of the study and the research questions
Step A
Thereisawealthofreportsinthemedicalliteratureonthehealthrisksthatworkcanposetoanemployee.Theaimofoccupationalsafetyleg-islationistosafeguardthehealthandsafetyoftheemployeesthroughriskidentification,eliminationofrisk,ormanagementoftheresidualrisk,iftheriskcannotbefullyeliminated.
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Healthproblemsinworkingageadults,however,arenotfullypre-ventable.Thereisahighbackgroundprevalenceofmusculoskeletalsymptomseveninthegeneralpopulation,andworkcanhavearoleasanadditionalriskfactorforMSD(Waddelletal.2006).AccordingtothegeneralprinciplesofpreventionintheEUframeworkdirectiveonhealthandsafetyatwork(89/391),combatingtherisksatsourceandadaptingtheworktotheindividualshouldalwaysbegivenpriorityoverindividualprotectivemeasuresandinstructionstotheworkers.
Step B
ThedisordermaycauseimpairmentintheactivityandparticipationdomainsoftheICFmodel.Atwork,thistypicallymeansthattheem-ployeecannotcontinueworking,butinsteadremainsabsentfromwork.Contextualfactorsseemtoplayamajorroleinthisprocess(Johanssonetal.2004;Shawetal.2009b).Ithasbeenshownthat(long-term)sicknessabsenceanddisabilityduetoMSDdependmoreonindividualandwork-relatedpsychosocialfactorsthanonbiomedicalfactorsorthephysicaldemandsatwork(Walker-Boneetal.2005).
Step C
SicknessabsenteeismasareflectionofdisablinghealthconditionisoneofthemajoroutcomesappliedinOHresearch.Duringthelastyears,however,moreattentionhasbeenpaidtotheimpactofhealthconditionsamongthoseemployeeswhocontinueatwork.Thefactthathealthproblemscauseinterferencewithworkhasbeenverifiedlately,andthetermsicknesspresenteeismhasbeenintroducedtoclarifythisphenomenon.
Step D
Absencefromworkisbeneficialfortherecoveryfromcertainillnesses.InMSDandmentaldisorders,however,itisobviousthatprolongedsicknessabsenceisamajorriskfactorforpermanentdisability.Again,thisislargelynotexplainedbymedicalgrounds,butpsychologicalandcontextualfactorsareessentialintheRTWprocess(Loiseletal.2005).
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Inordertoavoidthenegativeconsequencesofprolongedsickleave,thedisabilityhastobemanagedseparatelyfromthemanagementofthemedicalconditionitself.Theriskfactorsand,hence,themeanstoenhanceRTWprocessaredifferentfromthoseoftheunderlyinghealthdisorder.
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5. STUDY qUESTIONS AND hYPOThESES
1. Can the increased risk of LBP associated with heavy lifting at work be reduced by training the employees in correct lifting techniques or assistive devices? (StudyI)
BasedontheavailableevidenceonmanualmaterialhandlingasariskfactorforLBP,thehypothesisevaluatedinthissystematicreviewwasthat trainingcorrecttechniquesinliftingheavyloadsatworkand/orassistivedevicescouldreducetheriskofbackinjury(StepA).
2. What is the impact of disease and workplace characteristics on perceived work ability among employees seeking medical advice? (StudyII)
HowdoworkersvisitingtheirOHphysicianswithdifferentdiseases,andespeciallyMSD,assesstheircurrentworkability,andwhataretherelationshipsbetweentheworkers'perceptionsorexpectationsandself-assesseddisability?Thehypothesistestedwasthatperceivedpartialworkabilityandwork-relatednessofhealthproblemswouldbecommonandinterrelated(StepB).
3. How much productivity at work is impaired by medically verified UED?(StudyIII)
Productivitylosswhileatworkhasbeenshowntobecommonamongworkersreportingmusculoskeletalsymptoms.ThehypothesisforthissurveywasthatdiagnosedUEDwouldimpairworkperformanceeventhoughactualsickleavewouldnotbeneeded(StepC).
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4. Can productivity loss at work be reduced by an ergonomic in-tervention?(StudyIV)
Thestudyhypothesiswasthatproductivitylossatworkcouldbeusedasanoutcomeindicatorininterventionstudiesand,duringrecoveryfromUED,anindividuallytailoredergonomicinterventioncouldreduceproductivitylosscomparedtousualmedicalcare(StepC).
5. How can the effectiveness of part-time sick leave be evaluated in the management of MSD?(StudyV)
ThehypothesiswasthatarandomisedcontrolledtrialcouldbedesignedandimplementedintheFinnishOHStoinvestigatetheeffectsofpart-timesickleaveonreturntofull-timework(StepD).
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6. MATERIAL AND METhODS
6.1. Study populations
Inallindividualstudies,theparticipantswereworkingadults.Studiesincludedinthesystematicreview(studyI)wereperformedinhealthorhomecare(eightstudies)oramongbaggagehandlersorpostalworkers(threestudies).Thetotalnumberofparticipantsinthereviewwas18492.StudyIIincluded723employeesfromthechemicalindustryorpublicsector,whereas168to177employeesinstudiesIII–IVcamefromthehealthcareandcommercialsectors.
Therearesomedifferencesbetweenthestudieswithrespecttothehealthstatusofthestudypopulationsandtheuseofhealthservices(table5).Withtheexceptionofonestudy(II),inwhichpatientswereeligibleirrespectiveofanyhealthproblemsnecessitatingaconsultationwiththeOHphysician,allotherstudies(I,III–V)inthisthesisincludeonlysubjectswithMSD.
Table 5. Description of the included studies.
Type of study Population Study intervention
Main outcome
Study I
Systematic review Workers frequently exposed to heavy lifting
Lifting advice and/or devices
LBP and related sickness absence
Study II
Survey (questionnaire)
Workers seeking medical advice at OHS
- Self-assessed work ability, work-relatedness of the health problem
Study III
Survey (baseline assessment of rCT)
Workers with medically verified uED
- Self-assessed uED-related productivity loss at work
Study IV
rCT Workers with medically verified uED
Ergonomic advice and worksite visit
Self-assessed uED-related productivity loss at work
Study V
rCT(protocol)
Workers with medically verified MSD and in need of instant sick leave
Part-time sick leave
return to full-time work
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6MATERIALANDMETHODS
Thesystematicreview(studyI)summarisingtheevidenceonthepre-ventiveeffectsoftrainingandliftingequipmentonbackpainincludedstudieswithemployeesexposedtoheavyliftingatworkwhowerenotactivelyseekingtreatmentforcurrentbackpain.
Thesurvey(studyII)includedeachemployeeduringthestudyperiodcomingfortheirfirstappointmentwithanOHphysicianbecauseofanyhealthproblem.StudiesIIIandIVfocusedonlyonemployeeswithsymp-tomsintheupperextremitiesandnoneedforsickleave,whereasstudyVincludesallworkerswithanyMSDnecessitatingsickleave.TheemployeeswereexcludediftheconditionnecessitatedmedicalcareinstudyI,sickleaveinstudiesIII–IV,orthepainintensityscorewassevenormoreonascalefromzerototeninstudyV;ifthedisorderwascausedbymajortrauma,infection,orauto-immunedisease;ifthedisorderwascomplicatedbyanysevereco-morbidityorcondition(malignancy,fibromyalgia,mentaldisorder,occupationalinjuryordisease,scheduledorpriorsurgery);orthefollow-upinstudiesIV–Vwouldhavebeencomplicatedbyotherfactors(retirement,pregnancy,orotherlongerleavefromwork).
6.2. Methods
Theincludedfivestudiesrepresentthreedifferenttypesofstudies:systematicreview,survey(cross-sectionalquestionnaireandbaselineassessment)andRCT(table5).
6.2.1. Systematic review (Study I)
Thecurrentinterestinevidence-basedmedicinehasledtoanextensiveincreaseinthepublicationofsystematicreviewsandtothedevelopmentofmethodologicalguidelinesforsystematicreviews,becauseasystematicapproachisknowntobelesssusceptibletobiasthananarrativeapproach(vanTulderetal.1997;vanTulderetal.2003).
Thissystematicreviewincludedallstudieswithinterventionsthatmodifytechniquesforhandlingheavyobjectsorpatientsmanually,ifthestudyusedbackpain,consequentdisability,orsickleaveasthemainoutcome.Interventionsthatwerepermittedincludededucationalclasses,individualtrainingandinstructions,posters,leaflets,videos,audiotapes,orcombinationsofseveralinterventions.Inordertofindall
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relevantresearchreports,thesearchstrategydevelopedbytheCochranebackreviewgroupwasutilized(vanTulderetal.2003).TheprimarysearchfocusedonRCTswithasecondarysearchoncohortstudieswithaconcurrentcontrolgroup.
TheliteraturesearchwascarriedoutbetweenAugustandNovember2005.Searchstrategies,useddatabasesandthedetaileddescriptionofthereviewprocessaregivenintheCochraneLibraryversionofthereview(Martimoetal.2007).
Inordertomakeasecondaryanalysisusingrelevantcohortstudieswithaconcurrentcontrolgroup,thesensitivesearchstrategyforOHinterventionstudieswasapplied(Verbeeketal.2005).Twoauthorsscreenedtheobtainedtitlesandabstractsforeligibility.
ThemethodologicalqualityoftherandomisedtrialswasassessedusingthecriteriaandclassificationrecommendedbytheCochraneBackReviewGroup(vanTulderetal.2003).Thequalityofastudywasconsideredashighifmorethanhalfofthecriteriawerefulfilled.Fortheappraisalofcohortstudies,anothersetofcriteria(Slimetal.2003),validatedfornon-randomisedstudies,wereused.
Theprimaryanalysisofthereviewwasbasedontheevidencefromrandomisedtrialsonly.Inthesecondaryanalysisusingthecohortstud-ies,theresultsofeachcomparisonweresummarisedinaqualitativemanner.Thereafter,theconclusionswerecomparedfromtheprimaryandsecondaryanalyses.
6.2.2. Surveys (Studies II–III)
InstudyII,patientsattendingamedicalconsultationattwoOHcentres(oneinchemicalindustryandtheotherinpublicsectorinthecapitalarea)weregivenananonymousquestionnairebeforemeetingthephysician(N=12).Age,genderandoccupationwerecollectedtogetherwiththeresponsetoanopen-endedquestiononthenatureanddurationofthemaindiseaseorsymptomthatnecessitatedtheconsultation.Onlythefirstconsultationofeachpatientduringthestudyperiodwasincluded.
Patientassessedwork-ability(fullyorpartlyabletowork,disabled)andwork-relatednessofthehealthproblem("causedoraggravatedbywork"),andthepotentialofwork-relatedinterventionsinalleviatingthe
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6MATERIALANDMETHODS
symptoms.Patientsweretoldthattheirphysicianswouldnotseetheirresponses.Thephysicianswereaskedtoanswerthesamequestionsim-mediatelyaftertheconsultation.Onlypatientswhogavethesamereasonforthevisitasindicatedbytheirphysicianwereincludedintheanalysis.
StudyIIIwasalsocarriedoutincollaborationwiththreeOHunits.Allsubjectsaged18to60yearswereconsideredaspotentiallyeligible,iftheywereseekingmedicaladviceintheoccupationalhealthservices(OHS)becauseofupperextremitysymptomsthathadstartedorwereexacerbatedlessthan30dayspriortothemedicalconsultation('earlysymptoms').WithinthreedaysafterseekingmedicaladviceintheOHS,thesubjectwasexaminedattheFinnishInstituteofOccupationalHealth(FIOH)byaphysician,whodidnotparticipateinanalysingthedata.Theclinicaldiagnosiswasmadebyapplyingstandardizeddiagnosticcriteriaforeachsymptomentity(Sluiteretal.2001).
TheoutcomeofstudyIIIwasself-assessedproductivitylossatwork.ItwasassessedwithtwoquestionsabouttheimpactofUEDonworkperformance(QQmethod)duringtheprecedingfullworkday(Brouweretal.1999).Thefirstquestionwas:'Assesstheimpactofyourupperextremitysymptomsandmarkonascalefrom0("practicallynothing")to10("regularquantity")howmuchworkyouwereabletoperformascomparedtoyournormalworkday'.Thesecondquestionwas:'Assesstheimpactofyourupperextremitysymptomsandmarkonascalefrom0("verypoorquality")to10("regularquality")thequalityofyourworkascomparedtoyournormalworkday'.ThetranslationofthequestionsintoFinnishwasmadebasedontheoriginalDutchversionanditsEng-lishtranslationadheringtotheirwordingandstyleascloselyaspossible.ThevalidityoftheoriginalQQmethodhasbeenstudiedincomparisonwithothermeasurements(Brouweretal.1999;Meerdingetal.2005).Self-reportedproductivityonthismethodhasbeenshowntocorrelatewellwithobjectiveworkoutput(Meerdingetal.2005).
Adichotomousvariableforproductivityloss(yes/no)wasformedsothatthosewhoscoredavalue0–9ineitherofthetwoquestionswereclassifiedas'reportingproductivityloss',andwerecomparedtothosewhoscored10inbothquestions.Themagnitudeofproductivityloss(i.e.,howmuchproductivitywasreduced)wascalculatedusingtheformula[1–(quality/10)x(quantity/10)]x100 %,modifiedfromanearlierstudy(Hoeijenbosetal.2005).
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ThesubjectwasaskedtoratetheintensityofpaincausedbyUEDonascalefrom0to10(0correspondingto"nopain"and10to"theworstpossiblepain")andpaininterferencewithwork,leisuretimeandsleepduringthelastsevendays(from0,"nointerferenceatall",to10,"theworstpossibleinterference").SickleavesduetoUEDduringthepreceding12monthswerealsoinquired.
Fortheassessmentofphysicalexposuresatwork,theOHphysicianinterviewedthesubjectaboutthefrequencyofliftingloadsweighing5kgormore;workingwithhand(s)abovetheshoulderlevel;andwhetherworktasksrequiredfrequentorsustainedelevationsofthearms.Work-ingatakeyboard,prolongedforcefulgripping,aswellaspinchgripthateitherrequiredforcefulexertionordeviatedwristposture,werealsoinquired.Eachfactorwasdichotomizedusingacut-offofbeingexposedfor10 %oftheworktimeduringtheworkday.
JobstrainwasmeasuredwiththeJobContentQuestionnaire(Karaseketal.1998).Smokinghabitsandleisurephysicalactivitywereinquired,andwaistcircumferencewasmeasured.Fear-avoidancebeliefswereas-sessedusingfouritemsadaptedfromWaddelletal:"Physicalactivitymakesmysymptomsworse","Ifmysymptomsbecomeworse,itmeansthatIshouldstopwhatIwasdoing","Mypainiscausedbywork",and"Ishouldnotcontinueinmypresentjobbecauseofthesymptoms"(Waddelletal.1993;Estlander2003).
6.2.3. Randomised controlled trials (Studies Iv–v)
InstudyIV,theeffectivenessofaworkplacerelatedinterventionwasstudiedusingself-assessedproductivitylosscausedbyUEDasthemainoutcome.InformationfromstudyIIIservedasbaselinefortheinter-vention,andthefollow-uptimewas12weeks.Randomizationintointerventionandcontrolgroupswasperformedbythephysicianusingtablesofrandomnumbersinthreeblocks(symptomsinwristorforearm,elbow,orshoulder)andsealedenvelopes.Basedonpowercalculations,thetargetwastoinclude500subjectsinthestudy.
Allsubjectsreceivedthebestcurrentpracticetreatment(Varonenetal.2007).Thesupervisorsoftheemployeesintheinterventiongroupwerecontactedbyphonebythephysiciantodiscusspotentialaccom-modationsatwork.Afewdaysaftertheclinicalexamination,anoccu-
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pationalphysiotherapistvisitedtheworkplace.TheaimoftheworksitevisitwastoinvestigateergonomicimprovementsthatwereconsideredbeneficialfortherecoveryfromtheUED.Theassessmentincludedthephysicalworkenvironmentandtheavailabletoolsorinstruments,work-ingpostures,forcerequirements,workpaceandbreaksduringwork,aswellasassessingtheemployee'spossibilitiestocontinueworking.Theproposalswerediscussedtogetherwiththeemployeeandthesupervisorwhothenmadethefinaldecisiononthetechnicalandadministrativechangesrequiredtomodifytheworkload.
Theprimaryoutcomemeasurewasself-assessedproductivitylossatwork,asdescribedinstudyIII,measuredatbaseline,eightweeksand12weeks.Inaddition,theemployeeswereinquiredaboutthenumbersofsickleaveepisodesduetoanyreason,andexclusivelyduetoUED,dur-ingfollow-up.Thecontentsoftheergonomicinterventionsasreportedbythephysiotherapistsduringtheworkplacevisitswerealsoanalysed.
Theprotocolofthesecondinterventionstudy(studyV)aimstoassessthehealtheffectsofearlypart-timesickleavecomparedtoconventionalfull-daysickleave.Thisprotocolwasdesignedbasedontheresultsofpreviouslypublishedstudiesonpart-timesickleave(Kaustoetal.2008).Thefeasibilityofthestudydesignwasdiscussedandmodifiedwiththerepresentativesfromtheparticipatingworkplaces.PriortotheRCT,theprotocolandthequestionnairesweretestedbyoneOHSunitinapilotstudybasedonvoluntaryparticipationofsomeemployeesinpart-timesickleave.ThefinalprotocolwasapprovedbytheCoordinatingEthicsCommitteeofHospitalDistrictofHelsinkiandUusimaa.
ThisstudyVison-goingandthereforeonlytheprotocolisdescribedinthisthesis.InthosepatientswithMSDseekingmedicaladviceandfulfillinginclusioncriteria,theOHphysicianinvitesthesubjectsintothestudy.Thephysicianalsoinformstheemployeeaboutthestudyanditsaims,andiftheemployeeagreestoparticipate,informedconsentwillbesigned.Thisincludesapermissiontocontactthesupervisor,preferablyduringthepatient’svisit,inordertoinvestigatewhetherwork-relatedarrangementsforpart-timesickleavewouldbefeasible,inthecasethattheemployeeisallocatedtotheinterventiongroup.Ifthesupervisordisagrees,thentheworkerwillbeexcludedfromthetrial.
Oncetheagreementsfromtheemployeeandthesupervisorareobtainedandbeforetherandomisation,thephysiciandeterminesthe
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lengthofthesicknessabsencebasedonsymptoms,clinicalfindingsandbackgroundinformation.Subsequently,iftheemployeeisallocatedtopart-timesickleave(interventiongroup),dailyworkloadwillbereducedbylimitingtheworkingtime.Also,ifnecessary,remainingworktaskscouldbemodifiedsothatworkingispossibledespitethepresenceofsymptoms.Inthecontrolgroup,workloadiseliminatedbyfull-timesickleave.Bothgroupsreceiveappropriatemedicaladvice,andtheneedformedicaltreatmentsandacontrolvisitaredeterminedasusual.
6.3. Statistical analyses
6.3.1. Systematic review (Study I)
Fortheeligiblestudiesthatdidnotadjustforclusterrandomisation,thedesigneffectwascalculatedbasedonafairlylargeassumedintraclustercorrelationof0.10(Campbelletal.2001),followingthemethodsdefinedintheCochranehandbook(Deeksetal.2005).Thelengthoffollow-upwascategorizedasshortterm(lessthanthreemonths),intermediate(threeto12months)orlongterm(morethan12months).Thisclas-sificationisusedforthedescriptionoftheresults.
Forcomparisonswithdichotomousoutcomesandsufficientdata,theadjustedresultsofeachtrialwereplottedasoddsratios(ORs).Forcomparisonswithsimilarinterventionsbutwithbothdichotomousandcontinuousoutcomemeasurements,aneffectsizewascalculatedbasedonthelogarithmoftheORforstudieswithdichotomousoutcomes,andonthestandardisedmeandifferenceforstudieswithcontinuousoutcomes(Chinn2000).TheORsofstudieswerecombinedthatcomparedsimilarinterventionsandhavingmeasuredbackpainorbackinjurywithasimilarfollow-uptime.Theeffectsizesofstudieswithsimilarinterventionsthatmeasuredsicknessabsencerateordisabilityscoreatasimilarfollow-uptimewerecombinedbyusingthegenericinversevariancemethodusingthesoftwareasimplementedinRevMan4.2.forbothmeta-analyses.
6.3.2. Surveys (Study II–III)
InstudyII,factorsassociatedwithself-assessedworkabilitywerestudiedinamultinomiallogisticregressionmodel(SPSS®Programme,version
80
6MATERIALANDMETHODS
12.0.1).Theoutcomevariablewasworkabilityinthreelevels('able','par-tiallyable',and'unable').Theexplanatoryvariablesweregender,agegroup,occupationalstatus,OHcentre,durationofsymptoms,diseasegroup,work-relatednessofdiseaseandpotentialofwork-relatedinterventions.
LogisticregressionmodelswereusedinstudyIIItostudythedeter-minantsofproductivityloss.TheresultsarepresentedwithORswith95 %confidenceintervals(95 %CI).Multivariablemodelsincludedage,genderandthosevariablesassociatedwithproductivitylosswithaP-value<0.20inthegender-adjustedorage-andgender-adjustedmodels.Duetothecollinearityofpainintensityandpaininterference,nomutualadjustmentwasperformed,whereastheireffectswereassessedinseparatemodelsadjustedfortheothercovariates.Inadditiontotheseparateeffectsofpainintensity,excessivejobstrainandphysicalloadfactorsonproductivityloss,theirjointeffectswerealsoestimated,sinceitwashypothesizedthatthesevariablescouldactsynergistically.Multi-plicativeinteractionswerealsotestedbyincludinginteractionproductsinthemultivariablemodel.Thepossibleeffectmodificationbyagewasalsoinvestigatedwithstratifiedanalysesusingmedianage(45years)ascut-off.STATA,version8.2,softwarewasusedfortheanalyses.
6.3.3. Randomised controlled trials (Studies Iv–v)
DatainstudyIVwereanalysedaccordingtotheintention-to-treatprinciple.Missingdataonproductivityat12weeks(7inthecontrolgroupand8intheinterventiongroup)weresubstitutedwiththevalueat8weeks.Threeoutcomeswereused:proportionofproductivityloss(dichotomized),magnitudeofproductivityloss(continuous)andchangeinmagnitudeofproductivitylossfrombaseline(continuous).At8and12weeks,thetestfordifferences(two-tailed,P<0.05)waschi-squaredtestfortheproportionandtwo-samplet-testformagnitudeandchange.Generalizedestimatingequation(GEE)wasappliedtoanalyserepeatedmeasuresdata(Hanleyetal.2003).Thelinkfunctionwasspecifiedas"logit"forthedichotomizedoutcome.Inadditiontotheallocationgroupandfollow-uptime,age(continuous),gender,exposuretophysicalworkloadfactors(liftingloads>5kg,armelevationsatoraboveshoulderlevel,orforcefulorpinchgrip)andfear-avoidancebeliefs(continuous)wereincludedascovariatesinthemodels.
81
6MATERIALANDMETHODS
Itwasalsointendedtoidentifysomemodifiablesubgroupvariablesthatcouldaffecttheeffectivenessoftheintervention.Subgroupanalyseswereperformedbyusingthefollowingvariables:jobdemand,jobcontrol,fear–avoidancebeliefs(alldichotomizedusingthemedian),exposuretophysicalworkloadfactors,andpriorsicknessabsenceduetoUED.Totakeintoaccountthedifferenceinthemagnitudeofproductivitylossbetweentheinterventionandcontrolgroupatbaseline,thechangesinproductivitylossduringthefollow-upwereutilizedinthesub-groupanalyses.STATA,version10,software(StataCorpLP,CollegeStation,TX,USA)wasusedfortheanalyses.
InstudyV,asurvivalanalysiswillbeusedtostudythetimetoRTWintheinterventionandcontrolgroup.Theamountofsickleavedayswillbeanalysedat12and24months,andtheassociationsbetweentheoutcomesandbackgroundvariableswillbeanalysedusinggenerallinearmodels.Inaddition,thechangeinsymptomsanddisabilityindiceswillbestudiedatvarioustimepointsusinggenerallinearmodelsforrepeatedmeasurements.
Thecostsandbenefitstotheemployee,employerandsocietywillbeestimatedinbothstudygroups.CostsduetolostworkingtimewillbeanalysedseparatelytakingintoaccountthecompensationfromtheSocialInsuranceInstitutiontotheemployerduringfull-orpart-timesickleave.Dataoncostsoftheusedhealthservices,medications,andmedicalaids(duetothemainhealthproblem)willalsobecollected.Inaddition,theanalysiswillincludethecompensationofthelostworkinputusingstand-ins(salary,trainingtime)orovertime(performedbythecolleaguesofthestudysubjects),aswellasthetimethesupervisorusedtoaccommodatethenewworkarrangements.Allanalyseswillbemadebasedonanintention-to-treatprinciple.
Thenon-monetarybenefitswillbestudiedbasedonself-assessedpro-ductivityatwork(Brouweretal.1999),aswellasthereductionofpainanddisabilitymeasuredonascalefrom0to10.Ifthereisadifferencebetweenthegroupsintheoutcomemeasurements,acost-effectivenessanalysiswillbeundertakendividingthecostsbytheunitsofdifferenceintheoutcome.Ifthereisnosignificantdifferencebetweenthestudygroupsinanyofthehealthrelatedoutcomes,theanalysisoftotalcostsinbothgroupswillbeappliedindrawingthefinalconclusions.
82
7. RESULTS
7.1. Training and lifting devices for preventing back pain (Study I)
Altogether,3547titleswerefoundastheresultoftheprimarysearchstrategyinninedatabases.Thesensitivesearchstrategyprovided47additionaltitles.Another17referenceswerefoundinamanualsearch.Thusfromthetotalof3611articles,101wereselectedforcloserevalua-tion.Eighty-ninearticlesdidnotmeettheinclusioncriteria.Twoarticles(Fanelloetal.1999;Fanelloetal.2002)reportedonthesamestudy.Consequently,11studieswereincludedinthereview.
Fouroftheincludedstudieswereclusterrandomised(Daltroyetal.1997;vanPoppeletal.1998;Yassietal.2001;Krausetal.2002),twowereindividuallyrandomised(Reddelletal.1992;Mülleretal.2001),andfivewerecohortstudies(Dehlinetal.1981;Feldsteinetal.1993;Best1997;Fanelloetal.1999;Hartvigsenetal.2005).Two(Daltroyetal.1997;vanPoppeletal.1998)randomisedtrialsandallcohortstudieswerelabelledashighquality.Thecharacteristicsoftheincludedstudiesaredescribedintable6.
Inthreerandomisedtrials(Mülleretal.2001;Yassietal.2001;Krausetal.2002)andallfivecohortstudies,manualhandlingwasrelatedtopatientcare.Postalworkerswerestudiedinone(Daltroyetal.1997),andbaggagehandlersintwo(Reddelletal.1992;vanPoppeletal.1998)trials.Inallofthejobsstudied,theparticipantswereexertingsufficientstrainonthebackleavingampleroomforalleviationbyeffectiveinter-ventions.Thenumberofparticipantsinrandomisedtrialsvariedfrom51to12,772,andthefollow-uptimefrom6monthsto5.5years.Thecohortstudiesincluded45to345participants,andthefollow-uptimesvariedfrom8weeksto2years.
83
7RESuLTSTa
ble
6.
Ch
arac
teri
stic
s o
f in
clu
ded
stu
die
s
Des
ign
, p
arti
cip
ants
Inte
rven
tio
n v
co
ntr
ol
len
gth
of
follo
w-u
pO
utc
om
esM
eth
od
olo
gic
al
qu
alit
yD
altr
oy
1997
, uSA
Clu
ster
ran
dom
ised
35
97 p
osta
l wor
kers
Trai
ning
and
erg
onom
ic s
ite
visi
t v
stan
dard
tra
inin
g (v
ideo
)5.
5 ye
ars
Back
inju
ry r
ate
(dis
ablin
g an
d no
n-di
sabl
ing)
per
100
0 w
orke
r ye
ars
of e
xpos
ure
Hig
h (6
v 1
1)
Kra
us
2002
, uSA
Clu
ster
ran
dom
ised
, 12
772
hom
e ca
re
wor
kers
Safe
ty m
eetin
g v
back
bel
t,
no in
terv
entio
n28
mon
ths
Back
inju
ry r
ate
per
100
fu
ll tim
e eq
uiva
lent
sLo
w (5
v 1
1)
van
Popp
el
1998
, N
ethe
rland
s
Clu
ster
ran
dom
ised
, 31
2 ca
rgo
hand
lers
Trai
ning
v lu
mba
r su
ppor
t,
lum
bar
supp
ort
and
trai
ning
, no
inte
rven
tion
6 m
onth
sN
o of
sub
ject
s w
ith L
BP;
No
of s
ubje
cts
with
sic
k
leav
e an
d N
o of
day
s pe
r m
onth
with
LBP
; No
of d
ays
per
mon
th o
f si
ck le
ave
beca
use
of L
BP
Hig
h (8
v 1
1)
Yass
i 200
1,
Can
ada
Clu
ster
ran
dom
ised
, 34
6 nu
rses
“No
stre
nuou
s lif
ting”
v
“saf
e lif
ting”
pro
gram
me,
“u
sual
pra
ctic
e”
1 ye
arEx
perie
nced
wor
k re
late
d
LBP
and
its in
tens
ity d
urin
g pa
st w
eek;
Osw
estr
y di
s-ab
ility
que
stio
nnai
re; r
ate
of
back
or
trun
k re
late
d in
jurie
s
Low
(4 v
11)
Mül
ler
2001
, g
erm
any
rand
omis
ed,
51 n
urse
sTr
aini
ng v
exe
rcis
e in
sp
ace
curl
12 m
onth
sFr
eque
ncy
of L
BPLo
w (3
v 1
1)
redd
el 1
992,
u
SAra
ndom
ised
, 64
2 fle
et s
ervi
ce c
lerk
sTr
aini
ng v
bac
k be
lt, b
ack
belt
and
trai
ning
, no
inte
rven
tion
8 m
onth
sBa
ck in
jury
rat
e
(no
raw
dat
a av
aila
ble)
Low
(2 v
11)
Fane
llo 1
999,
Fr
ance
Coh
ort
stud
y,
272
nurs
es a
nd c
lean
ers
Trai
ning
and
fee
dbac
k at
wor
k v
no in
terv
entio
n2
year
sPr
eval
ence
of
LBP
Hig
h (8
v 1
2)
Best
199
7,
Aus
tral
iaC
ohor
t st
udy,
55
nur
ses
Trai
ning
v in
-hou
se o
rient
atio
n12
mon
ths
Self
repo
rted
LBP
dur
ing
pa
st w
eek
and
past
yea
rH
igh
(8 v
12)
Deh
lin 1
981,
Sw
eden
Coh
ort
stud
y,
45 n
urse
sTr
aini
ng v
phy
sica
l exe
rcis
e,
no in
terv
entio
n8
wee
ksFr
eque
ncy
of lo
w b
ack
sy
mpt
oms
Hig
h (7
v 1
2)
Feld
stei
n
1993
, uSA
Coh
ort
stud
y,
55 n
urse
sTr
aini
ng, p
ract
ical
fee
dbac
k v
no in
terv
entio
n1
mon
th“C
ompo
site
bac
k pa
in”
Hig
h (7
v 1
2)
Har
tvig
sen
20
05, D
enm
ark
Coh
ort
stud
y,
345
nurs
esTr
aini
ng v
one
inst
ruct
iona
l m
eetin
g2
year
sN
o of
epi
sode
s an
d N
o of
da
ys w
ith L
BP d
urin
g pa
st
year
Hig
h (9
v 1
2)
84
7RESuLTS
Thetraininginterventionsfocusedonliftingtechniques,andtheirdura-tionvariedfromasinglesessiontoonceaweektrainingforaperiodoftwoyears(Table7).Inthreestudies,thetrainingwassupportedbyfollow-upandfeedbackattheworkplace.Theadvocatedliftingtechniqueswerenotdescribedindetail.Theinvolvementofsupervisorswasclearlyindicatedinthreestudies,andtheencouragementtouseavailableliftingaidswasstatedinfivestudies.Aprofessionalinstructorwasusedinmoststudies.
Compliancewiththeinstructionsandwiththeuseofassistivede-viceswasmonitoredinfivestudies(Feldsteinetal.1993;Best1997;vanPoppeletal.1998;Yassietal.2001;Hartvigsenetal.2005).Threestudiesreportedpositivechangesinliftingtechniquesinthreestudiesandthereweremarginalornochangesintwostudies.Inaddition,onestudy(Daltroyetal.1993)hasreportedseparatelythattheinterventionresultedinincreasedknowledgebutnotinanysignificantimprovementofmanualhandlingbehaviour.
Comparisonbetweengroupsreceivingtrainingornointerventionintworandomisedtrials(vanPoppeletal.1998;Yassietal.2001)in-dicatedthattherewasnodifferenceintheamountofbackpain(OR0.99,95 %CI0.54to1.81)orrelateddisability(effectsize0.04,95 %CI–0.50to0.58)atintermediatefollow-up.Thesameresultwasob-tainedinanotherrandomisedtrial(Reddelletal.1992),whichwasnotincludedinthemeta-analysisbecauseinsufficientdatawerereported.Onerandomisedtrial(Krausetal.2002)showednoeffectinbackpainatlong-termfollow-up(OR1.07,95 %CI0.06to17.96).Theresultsofthreecohortstudiessupportedthoseoftherandomisedstudiesatshort-term(Dehlinetal.1981;Feldsteinetal.1993)andlong-termfollow-up(Fanelloetal.1999).
Trainingcomparedtominoradvice(video)inonerandomisedtrial(Daltroyetal.1997)didnotshowaneffectonbackpainatlong-termfollow-up(OR1.08,95 %CI0.56to2.08).Thisconclusionwassup-portedbytheresultsoftwocohortstudies(Best1997;Hartvigsenetal.2005)usingin-houseorientationorlessextensivetrainingasthecontrolinterventions.
Comparisonoftrainingandlumbarsupportusedidnotyieldasignificantdifferenceinbackpainatintermediatefollow-upaccordingtoonerandomisedtrial(Reddelletal.1992).Anotherrandomisedtrial(Krausetal.2002)cametoasimilarconclusionwithrespecttolong-termfollow-up(OR1.04,95 %CI0.06to17.38).
7RESuLTSTa
ble
7.
Det
ails
of
inte
rven
tio
ns
in s
tud
ies
aim
ed a
t p
reve
nti
ng
bac
k in
jury
an
d p
ain
cau
sed
by
lifti
ng
an
d h
and
ling
pat
ien
ts
or
hea
vy o
bje
cts
Stu
dy
No
an
d
du
rati
on
of
sess
ion
sTi
me
span
o
f tr
ain
ing
Trai
nin
g a
s d
escr
ibed
in
art
icle
Trai
nin
g
met
ho
ds*
Man
agem
ent
com
mit
men
t
Use
of
as
sist
ive
dev
ices
erg
on
om
ic
inte
rven
tio
n(s
) in
clu
ded
Rei
nfo
r-ce
men
t in
clu
ded
Dal
troy
2 x
1.5
hour
s1
wee
kPr
oper
lift
ing
and
carr
ying
tec
hniq
ues
BYe
sN
oYe
sYe
s
Kra
usu
ncle
aru
ncle
arSa
fety
pra
ctic
es w
hen
hand
ling
patie
nts
unc
lear
Not
men
tione
dN
oN
oN
o
van
Popp
el3
x 1.
5-2
hour
s12
wee
ksA
nato
my
and
liftin
g te
chni
ques
BN
ot m
entio
ned
No
No
No
Yass
i1
x 3
hour
sSi
ngle
tr
aini
ng“S
afe
liftin
g” o
r “n
o st
renu
ous
lif
ting.
” H
andl
ing
tech
niqu
es c
oupl
ed
with
ava
ilabl
e eq
uipm
ent
BN
ot m
entio
ned
Enco
u-ra
ged
No
No
Mül
ler
unc
lear
unc
lear
unc
lear
unc
lear
Not
men
tione
du
ncle
aru
ncle
aru
ncle
ar
redd
el1
x 1
hour
Sing
le
trai
ning
Bala
ncin
g lo
ad, p
ivot
ing
inst
ead
of
twis
ting,
get
ting
clos
e to
load
, sq
uat
lift,
squ
arin
g lo
ad, m
aint
aini
ng
thre
e po
int
cont
act
BN
ot m
entio
ned
No
No
No
Best
32 h
ours
(in
tot
al)
unc
lear
Sem
isqu
at p
ostu
re a
nd w
eigh
t
tran
sfer
tec
hniq
ues
such
as
br
acin
g, p
ivot
ing,
lung
ing,
and
co
unte
rbal
anci
ng lo
ad
unc
lear
Not
men
tione
dN
oN
oN
o
Deh
lin8
x 45
min
8 w
eeks
Shor
t le
ver
arm
s du
ring
liftin
g,
min
imis
ing
wei
ght
of b
urde
n by
lift
ing
toge
ther
AN
ot m
entio
ned
Enco
u-ra
ged
No
No
Fane
llo6
(le
ngth
unc
lear
)6
days
Met
hod
revi
sed
by P
aul D
otte
as
ap
plie
d al
so b
y Be
st e
t al
unc
lear
Not
men
tione
dEn
cou-
rage
dN
oYe
s
Feld
stei
n1
x 2
+ 8
hou
rs2
wee
ksSp
ecifi
c te
chni
que
for
patie
nt t
rans
fer
BYe
sEn
cou-
rage
dN
oN
o
Har
tvig
sen
104
x 1
hour
+
4 x
2 ho
urs
2 ye
ars
“Bob
ath
prin
cipl
e”B
Yes
Enco
u-ra
ged
No
Yes
*A=
leas
t en
gagi
ng (l
ectu
res,
pam
phle
ts, v
ideo
s); B
=m
oder
atel
y en
gagi
ng (p
rogr
amm
ed in
stru
ctio
ns, f
eedb
ack
inte
rven
tions
); C
=m
ost
enga
ging
(tra
inin
g in
beh
avio
ural
mod
ellin
g, h
ands
-on
trai
ning
).
86
7RESuLTS
Trainingandphysicalexercisewerecomparedinonerandomisedtrial(Mülleretal.2001)andnodifferenceinbackpainwasfoundattheintermediatefollow-up.Theresultsofonecohortstudy(Dehlinetal.1981)providedsupporttotheconclusionmadeattheshort-termfollow-up.
Agroupreceivingtrainingandassistivedeviceswascomparedtothegroupsreceivingtrainingonlyornointerventionatallinonerandomisedtrial(Yassietal.2001).Nodifferenceinbackpainwasshownininterme-diatefollow-upofeithercomparison(OR0.42,95 %CI0.04to4.99).Inaddition,therewasnodifferenceinrelationtobackrelateddisability.
7.2. factors associated with self-assessed work ability (Study II)
Atotalof971consecutivepatientswereenrolledby12physicians.Questionnairescompletedbyboththepatientandthephysicianwereavailablefor950visits(98 %).Thestatisticalanalysesfocusedon723(76 %)visits,wherethereasonforthecontactgivenbythepatientandthediagnosismadebythephysicianwereinthesamemajordiseasegroup.
MSD(39 %)wasthemostcommonreasonforthevisit,followedbyrespiratory(17 %),cardiovascular(11 %),dermatological(9 %),mental(7 %),and"other"disorders(16 %).Inmostcasesthedurationofthesymptomswaslongerthansixmonths.Respiratorysymptomshadlastedforlessthantwoweeksinhalfofthecases.
Table 8. Self-assessed ability to work by the main diagnosis of the visit
Disease groupSelf-assessed ability to work
N able (%)
Partially able (%)
Unable (%)
Cannot say (%)
Musculoskeletal 283 51 28 16 5
respiratory 125 58 24 10 8
Cardiovascular 83 80 16 4 1
Dermatological 67 96 4 0 0
Mental 47 40 30 23 6
Other 118 74 19 6 2
TOTAL 723 63 22 11 4
87
7RESuLTS
Sixty-threepercentofthepatientsreportedbeingabletoworkdespitetheirhealthproblem(table8).Intotal,partialworkabilitywasreportedby22 %andfulldisabilityby11 %ofthepatients.Thosewithmentaldisordersreportedfullorpartialdisabilitymostoften(in53 %ofthecases),followedbythosewithMSD(44 %).
Thepatientsregardedmental(85 %)andMSD(74 %)mostoftenasbeingatleastpossiblywork-related(table9).Thephysiciansweremorecautiousinassessingwork-relatednessineverydiseasecategory.Ingeneral,theyregardedthereasonaswork-relatedin13 %andpossiblywork-relatedin21%ofthevisits.Thedisordersmostoftenregardedaswork-relatedbythephysicianswerementalproblems(26 %)andMSD(22 %).
Table 9. Work-relatedness assessed by patients and physicians by the main diagnosis of the visit
N Not work-related (%)
Possibly work-related (%)
Work-related (%)
Cannot say (%)
Musculoskeletal 283
- Patients 18 41 33 8
- Physicians 42 34 22 2
respiratory 125
- Patients 51 32 6 10
- Physicians 86 8 4 2
Cardiovascular 83
- Patients 31 51 8 10
- Physicians 71 22 6 1
Dermatological 67
- Patients 66 12 6 16
- Physicians 88 7 3 1
Mental 47
- Patients 13 36 49 2
- Physicians 40 32 26 2
Other 118
- Patients 49 24 9 18
- Physicians 85 6 6 3
TOTAL 723
- Patients 34 35 20 11
- Physicians 64 21 13 2
88
7RESuLTS
Work-relatedinterventionswereconsideredasbeneficialbythepa-tientsinonethirdofthecases,mostfrequentlywhenthereasonforthevisitwasamentalproblem(56 %)orMSD(39 %).
Inthemultinomiallogisticregressionmodel,genderhadnoeffectonself-assessedworkability(table10),butolderagemarkedlyincreasedtheriskofdisability.Bluecollaremployeesranahigherriskofbothpartialandfulldisabilitycomparedtoupperwhitecollaremployees.Ashortdurationofthesymptomswasassociatedwithbothpartialandfulldisabilitytowork.
Table 10. Odds ratios (OR) and 95 % confidence intervals (CI) for the adjusted effects of the patient and disease characteristics on self-assessed ability to work
Self-assessed ability to workPartially ablea Unablea
Predictor OR 95% CI OR 95 % CIGender (male vs. female) 1.1 0.6–2.0 0.9 0.4–2.2
age (reference category '35 years or less')
– 35–44 years 1.2 0.6–2.5 4.8 1.2–18.6
– 45–54 years 1.1 0.5–2.2 4.3 1.1–17.1
– 55 years or older 1.6 0.7–4.0 8.9 1.9–41.4
Occupational group (reference category 'upper white collar')
– lower white collar 1.8 0.8–4.3 2.4 0.6–9.2
– blue collar 6.5 2.6–16.4 8.1 2.0–33.2Duration of the symptoms before the visit (reference category 'more than 6 months')
– 2–6 months 1.0 0.4–2.2 1.5 0.5–4.3
– 2 weeks to 2 months 2.0 0.8–4.5 0.6 0.1–2.6
– less than 2 weeks 3.4 1.6–7.5 3.7 1.3–10.7
Disease group ('other disease incl. skin diseases' as reference category)
– musculoskeletal 2.5 1.2–5.1 7.7 2.2–26.6
– respiratory 2.4 1.1–5.6 2.7 0.7–10.6
– cardiovascular 1.7 0.6–4.5 2.0 0.3–14.1
– mental 2.1 0.7–6.4 17.5 3.5–86.3
Assessment of work-relatedness
– 'possible' vs. 'no' 2.9 1.4–6.0 1.3 0.4–3.7
– 'yes' vs. 'no' 5.2 2.1–12.8 12.8 3.9–41.9
Potential of work-related interventions
– 'possible' vs. 'no' 1.6 0.8–3.0 0.5 0.2–1.2
– 'yes' vs. 'no' 2.0 0.9–4.6 0.2 0.1–0.8
OH centre (A vs. B) 1.1 0.5–2.2 3.4 1.2–9.7a reference category patients with self-assessed normal ability to work
89
7RESuLTS
MSDincreasedtherisksofbothpartialandfulldisability.Thehigh-estriskoffulldisabilitywasobservedformentaldisorders.Theriskofpartialworkabilitywasincreasedforrespiratorydiseases.Self-assessedwork-relatednessofthediseaseincreasedtherisksofbothpartialandfulldisabilitytowork,whereastheriskoffulldisabilitywassignificantlyreduced,ifthepatientconsideredwork-relatedinterventionsasbeingbeneficial.
TheOHcentrehadastatisticallysignificanteffectondisability,buteliminatingthisvariablefromthemodeldidnotaffecttheriskestimatesoftheothervariables.
7.3. Self-assessed productivity loss caused by upper extremity disorders (Study III)
Therecruitmentwasendedasplannedeventhoughthetargetof500studysubjectswasnotachieved.Thiswasduetothesmallerthanexpectednumberofsubjectsfulfillinginclusioncriteria,aswellastherelativelyslowrecruitingprocessingeneral.Altogether222subjectsparticipatedinthestudy.Forty-fivesubjectswereexcludedbecausetheydidnotmeetthecriteriaforeligibility,leaving177subjectstothestudy.Afterexclu-sionofafurtherninesubjectswithmissinginformationonproductivity,168subjects(95 %)wereincludedintheanalyses.Themostcommonoccupationswerenursesandotherhealthcareworkers(64 %),secretariesandotherclericalworkers(25 %),andwarehouseworkers(8 %).Themajority(87 %)werefemale,andtheaverageagewas45years.
ThemostprevalentUEDwereepicondylitis(29 %),specificshoulderdisorder(28 %)andnon-specificupperlimbpain(26 %).Thesubjectsreportedpainintensityandpaininterferencewithworktobeonaver-age4.7(max10)and4.8,respectively.Paininterferencewithsleepwassomewhatlower(3.3).SicknessabsenceduetoUEDduringthelast12monthswasreportedby37 %ofthesubjects.Workingatakeyboardandliftingloadswerethemostcommonphysicalworkloadfactors.Highjobstrainwasreportedby27 %ofthesubjects.Everyseventhsubjecthadelevatedscoresonfear-avoidancebeliefs,andeverysecondperceivedtheirdisorderasbeingwork-related.
Morethanhalfofthesubjects(56 %ofwomen,59 %ofmen)reportedthattheUEDhaddecreasedtheirproductivity.Theaverage
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productionlosswas34 %duringthepreviousworkday,correspondingtoanaverageof19 %lossofproductivityamongallstudysubjects.
Ageandgenderwerenotassociatedwithproductivityloss(table11),andneitherweresmokinghabits,waistcircumferenceorphysicalactivity.Subjectsinthediagnosticcategory"other",mainlywithmedianorulnarnerveentrapment,wereatthehighestriskofproductivityloss.
Table 11. Odds ratios (OR) of productivity loss adjusted for gender and age* or gender alone** according to background characteristics
Characteristic all* 20-45 yrs** 46-64 yrs**OR 95 % CI n OR 95 % CI n OR 95 % CI
gender
Female (reference category) 67 79
Male 1.2 0.4-3.0 13 1.5 0.4-4.9 9 0.9 0.2-3.6
Age (continuous) 1.00 0.97-1.04 - -
Diagnosis
Epicondylitis (reference category) 25 24
Shoulder disorder 1.5 0.6-3.5 21 1.4 0.4-4.6 26 1.6 0.5 -4.9
Wrist tenosynovitis 1.7 0.5-5.3 8 4.2 0.6-26.3 9 0.8 0.2-3.7
Nonspecific pain 1.9 0.8-4.4 23 2.3 0.7-7.4 20 1.5 0.4-5.0
Other 6.2 1.2-31.4 3 9 3.5 0.6-20.4
Pain intensity
1st tertile (reference category) 26 27
2nd tertile 3.7 1.6-8.2 28 3.3 1.1-10.3 27 4.0 1.3-12.6
3rd tertile 3.0 1.4-6.6 26 3.1 0.99-9.6 30 2.9 0.98-8.6
Pain interference with work
1st tertile (reference category) 23 31
2nd tertile 2.7 1.2-5.9 24 1.9 0.5-6.4 30 3.6 1.2-10.5
3rd tertile 6.2 2.6-14.4 32 6.7 2.0-22.3 23 5.1 1.5-16.9
Pain interference with leisure time
1st tertile (reference category) 21 31
2nd tertile 1.7 0.8-3.7 32 1.4 0.4-4.2 25 2.2 0.7-6.5
3rd tertile 1.8 0.8-3.8 27 1.4 0.4-4.3 28 2.2 0.7-6.2
Pain interference with sleep
1st tertile (reference category) 26 26
2nd tertile 1.6 0.7-3.4 31 0.7 0.2-2.2 25 4.2 1.3-13.5
3rd tertile 2.5 1.1-5.5 23 1.0 0.3-3.2 33 6.0 1.9-18.6
Table 11. continues...
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Characteristic all* 20-45 yrs** 46-64 yrs**OR 95 % CI n OR 95 % CI n OR 95 % CI
Physical exposures at work
Lifting loads, >5 kg
No (reference category) 52 68
Yes 2.1 0.99-4.5 28 1.9 0.7-5.1 18 2.3 0.7-7.2
Arm elevations or above shoulder
No (reference category) 67 77
Yes 1.9 0.7-4.9 13 2.1 0.5-7.6 9 1.6 0.3-6.8
Forceful or pinch grip
No (reference category) 69 80
Yes 1.5 0.5-4.4 11 1.5 0.4-5.8 6 1.6 0.2-9.1
Working at a keyboard
No (reference category) 39 45
Yes 0.7 0.3-1.4 41 1.4 0.5-3.5 41 0.4 0.2 -1.1
Previous sickness absence (past 12 months)
No (reference category) 46 60
Yes 2.2 1.1-4.3 34 3.4 1.3-8.7 28 1.5 0.5-3.7
High job strain
No (reference category) 50 64
Yes 1.3 0.6-2.8 23 3.9 1.3-11.8 20 0.5 0.2-1.4
Elevated score on fear-avoidance beliefs
No (reference category) 69 75
Yes 3.5 1.2-9.9 11 4.6 0.9-23.1 13 2.8 0.7-10.9
Painintensity,paininterferencewithwork,andfear-avoidancebeliefswereassociatedwithproductivityloss.Paininterferencewithsleepwasalsoassociatedwithproductivityloss,butonlyintheolderagegroup.
Withrespecttothephysicalexposuresatwork,onlyliftingatworkshowedanassociationwithproductivityloss.Highjobstrainandpriorsickleavewereassociatedwithproductivityloss,butonlyamongtheyoungersubjects.Iftheyoungersubjectswereconvincedaboutwork-relatednessofthedisorder(responseinthethirdtertile),theprevalenceofproductivitylosswasincreased(OR4.5,95 %CI1.2–16.6).Nosimilarassociationwasfoundintheoldersubjects.
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Inamutuallyadjustedmodelwithgender,age,painintensity,physicalexposuresatwork,previoussicknessabsence,highjobstrainandfear-avoidancebeliefs,onlypainintensityandfear-avoidancebeliefsshowedassociationswithproductivityloss.PaininterferencewithworkwasalsoassociatedwithproductivitylosswithanORof2.5(95 %CI1.1–5.7)forthe2ndtertileand5.7(95 %CI2.2–14.3)forthe3rdtertile,whenitwasincludedinthemodelinsteadofpainintensity.Intheyoungerworkersonlyhighjobstrain,andintheolderworkersonlypaininter-ferencewithsleep,remainedstatisticallysignificantafteradjustmentfortheotherfactors.
Theseparateandjointeffectsofphysicalworkloadfactors,painin-tensityandjobstrainonproductivitylosswerealsostudied.Ingeneralintheyoungersubjects,acombinationofanytwoofthesefactorswasassociatedwithahigherdegreeofproductivitylossthanthepresenceofonlyonefactor.Highjobstrainseemedtocontributemosttotheproductivitylossandphysicalexposurestheleast.Whentheinterac-tionproductswereincludedinthelogisticregressionmodels,onlytheinclusionoftheinteractionbetweenphysicalloadsandpainintensityimprovedthegoodness-of-fitofthemodel.
7.4. Effectiveness of an ergonomic interven-tion on productivity loss (Study Iv)
Atotalof177participantswererandomisedtotheintervention(91subjects)andcontrolgroup(86subjects).Duringthe12weekfollow-up,theparticipationratewas87 %intheinterventiongroupand88 %inthecontrolgroup.
Mostparticipantswerefemaleinbothgroups.Therewasnomajordif-ferenceinthedistributionofageandlife-stylerelatedriskfactorsbetweentheinterventionandcontrolgroup.Painintensity,paininterferencewithwork,leisuretimeandsleep,aswellastheprevalenceofprevioussickleavesandhighjobstrainwerealsosimilarinthetwogroups.Bothgroupshadsimilarmeanscoresforthefear-avoidancebeliefs;however,elevatedscoresonfear-avoidancebeliefswerefoundalmosttwiceasoftenintheinterventiongroupasinthecontrolgroup(18 %versus11 %).Specificshoulderdisordersweremoreprevalent(35 %versus21 %)
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andexposuretoliftingatworkwasmorefrequent(38 %versus18 %)inthecontrolgroupthanintheinterventiongroup.Allcasesof“otherUED”belongedtotheinterventiongrouponly.
Fromatotalof531potentialobservations,465(88 %)wereincludedintheanalyses.Nineobservationsatbaseline,36at8weeksand21at12weekswereexcluded.Incomparisonwiththoseincludedintheanalyses,theexcludedsubjectswereyounger(meanage42versus46years),theyhadhigherscoresonpainintensity(5.4versus4.7),andtheyhadbeenmoreoftenonsickleavepriortotheenrolment(57 %versus36 %).Inaddition,theexcludedemployeesweretwiceasoftenexposedtoliftingatworkthantheemployeesincludedintheanalyses(46 %versus28 %).
Withrespecttothe66excludedobservations,30(46 %)wereinthecontrolgroupand36(55 %)intheinterventiongroup.Thoseexcludedfromtotheinterventiongroupmorecommonlyreportedexposuretolifting>5kg(53 %versus34 %),andhadahigherlevelofpainintensity(mean5.6versus5.1),paininterferencewithwork(mean5.5versus4.7),paininterferencewithleisuretime(mean5.4versus4.2),andpaininterferencewithsleep(mean4.2versus2.4)atbaselineincomparisontotheexcludedsubjectsinthecontrolgroup.Ontheotherhand,excludedsubjectsintheinterventiongrouplessfrequentlyreportedproductivityloss(among39subjects,magnitude13 %versus30 %)andelevatedscoreonfear-avoidancebeliefs(0versus18.5 %)thanthoseexcludedinthecontrolgroup.Nodiffer-enceswerefoundwithrespecttoage,jobstrainandsicknessabsencepriortotheenrolment.
Eightweeksaftertheenrolment,almostallsubjects(92 %)intheinterventiongroupbutonly8 %inthecontrolgroupreportedthatanoccupationalphysiotherapisthadvisitedtheirworkplace.Theer-gonomicassessmentwasmostoftenmadetogetherwiththeemployeealone,andthesupervisorhadparticipatedin17 %oftheassessments.Atotalof412implementedorplannedmeasureshadbeenidentified.Themajority(60 %)wererelatedtoguidingtheemployeeinselfcare,workingposture,useoftoolsandinstruments,usingbothhandsinworktasks,andreorganisinghowtheworkwasdone.Therecom-mendationstobeimplementedintheimminentfuture(25 %ofthemeasures)includedpurchasinganewaidortool,andreorganisingworkoritsenvironment.Themodificationsatworkmadeduringthevisit
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(16 %ofthemeasures)includedchangestothekeyboardandmonitor,structuresoftheworkplace(includingarmrests),andadjustmentstothetableandthechair.
Productivitylossatbaselinewasreportedby53.8 %intheinterven-tiongroupand57.9 %inthecontrolgroup(figure5).At8weeks,boththeproportionandmagnitudeofproductivitylosswerelowerintheinterventionthaninthecontrolgroup.However,thedifferenceswerenotstatisticallysignificant.At12weeks,theproportionandmagnitudeofproductivitylosswerestatisticallysignificantlylowerintheinterventionthaninthecontrolgroup(proportion25 %versus51 %andmagnitude7 %versus18 %,respectively,P=0.001forboth).
TheanalysisofrepeatedmeasuresusingGEErevealedstatisticallysignificantdifferencesintheproportionandmagnitudeofproductivitylossbetweentheinterventionandcontrolgroupafteradjustmentforage,gender,physicalworkloadfactors,fear-avoidancebeliefsandfollow-
1
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Baseline (N = 168) 8 weeks (N = 141) 12 weeks (N = 156)
Proportion (control)Proportion (intervention)Magnitude (control)Magnitude (intervention)
FigurE 5. Proportion and magnitude of productivity loss (on a logarithmic scale) at baseline, eight and twelve weeks after the intervention in the con-trol and intervention groups.
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uptime.Therewasaninteractionbetweeninterventionandtime,theproportion(P=0.009)andmagnitude(P=0.033)ofproductivitylossbeinglowerintheinterventiongroupthaninthecontrolgrouponlyat12weeks.
Intheemployeeswithoutanyproductivitylossatbaseline,15.6 %intheinterventiongrouphaddevelopedproductivitylossat8weeks,whereasthisproportionwasalmosttwo-foldinthecontrolgroup.Themagnitudeofproductivitylosswas3.7 %and8.1 %,respectively.At12weekstherewasalmosta4-folddifferenceintheproportionandan8-folddifferenceinthemagnitudebetweentheinterventionandcontrolgroup.WithGEEanalyses,thedifferenceswerenotedtobestatisticallysignificant.
Amongemployeeswithproductivitylossof10–20 %atbaseline,thereductioninmagnitudeofproductivitylosswasmoreprominentintheinterventiongroupthanoccurredinthecontrolgroupat8weeksand12weeks.At12weeksalsotheproportionofproductivitylosswaslowerintheinterventionthaninthecontrolgroup.Ifthebaselineproductivitylosswashigherthan20 %,therewerenosignificantdif-ferencesbetweenthestudygroupsintermsofproductivitylossduringthefollow-up.
Theimprovementofproductivityat12weekswassignificantlybetterintheinterventiongroupthaninthecontrolgroupinthesubsampleofsubjectswithnoworkingatakeyboardatworkbutexposuretootherphysicalworkloadfactors(P=0.033),withlowjobdemands(P=0.036),amongthosewithnosicknessabsenceduetoUEDbeforethestudy(P=0.043),aswellasthosewithlowfearavoidance(P=0.033).Theimprovementdidnotdifferbetweeninterventionandcontrolgroupsinthosewithloworhighjobcontrol.
Amongthosewhohadbeenonsickleaveforanyreasonduringfourweeksprecedingthefollow-upat12weeks,therewasnodifferenceinthechangeofproductivitybetweentheinterventionandcontrolgroups.Incontrast,thoseindividualsintheinterventiongroupwhohadnotbeenonsickleave,hadahigherimprovementinproductivityat12weekscomparedwiththecontrolgroup(6.5versus2.4%,P=0.033).
Therewasnodifferencebetweenthecontrolandinterventiongroupinpainintensityat12weeks(mean2.6versus2.9)orinpaininterfer-encewithwork(mean2.4versus2.5).
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7.5. Early part-time sick leave in musculoskeletal disorders (Study v)
Duringthepilotstudythereweresomechallengesrelatedtofindingeli-gibleindividualsattheOHS,anextraworkloadontheOHphysiciansinimplementingtheinterventiontotheemployeesandthesupervisors,aswellasthemanypracticalissuesrelatedtoadministrativequestionsatworkduringpart-timesickleave.However,thearrangementsattheworkplacewereusuallyconsideredasbeingfeasibletoimplementandtheattitudeofthesupervisorsandco-workerswasmostlypositiveandsupportive.ThisprovidedanimpetustoinitiatetheactualRCTatthebeginningof2008.TherecruitmentperiodofthisstudyendedinDe-cember2009,butthefollow-upwillnotenduntilDecember2010,andthereportingoftheresultswillstartin2011.
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8. DISCUSSION
8.1. Main findings
8.1.1. Primary prevention of low back pain and related disability
Wefoundnoevidencethattrainingwithorwithoutliftingequipmentwouldbeeffectiveinthepreventionofbackpainorconsequentdisabil-ity(studyquestionNoI).Thereasonmaybethateithertheadvocatedtechniquesdidnotreducetheriskofbackinjury,ortrainingdidnotleadtoanadequatechangeinliftingandhandlingtechniques.Therewerenodifferencesintheresultsbetweentheanalysesfromstudieswithdifferentdesignsorwithdifferenttypesofliftingandhandling.Tworandomisedcontrolledtrialspublishedlaterlentsupporttothepresentresults(Jensenetal.2006;Lavenderetal.2007).
Oneexplanationforthelackofanyeffectcouldbethattheinterven-tionwasnotappropriate.Astrainingmethodsbecomemoreengaging,workersacquiremoreknowledgeandthenumberofinjuriesdeclines(Burkeetal.2006).Accordingly,thetrainingmethodswereclassifiedbasedonlearners’participation,butthereviewfailedtodetectamorepositiveoutcomeforstudiesthatinvolvedmoreintensetrainingmethods.
Theriskofbackpainmightberelatednottoincorrecthandlingtechniquesbuttootherwork-relatedfactorsinherentinthepopulationsstudied(suchasnon-neutral,bent,orrotatedtrunkpostureswithoutliftingorhandling,orpsychosocialstrain).Itwasnotpossibletotestthishypothesis,however,becausenoneofthestudiesdescribedthecontextoftheinterventioninsufficientdetailtoenablefurtheranalysis.Ithasalsobeenarguedthatthesizeoftheeffectofwork-relatedphysicaldemands
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islessthanthatofotherindividual,non-occupationalandunidentifiedfactors(Waddelletal.2001).
OnereasonwhytrainingincorrectliftingtechniquesandassistivedevicesdidnotreduceLBPorrelateddisabilityismostlikelythecom-plexityoftheimpactofphysicalandpsychosocialriskfactorsatwork.AsproposedbythemodelofCoxetal(Figure3),evenphysicalloadfactorswhichhaveaninfluenceontheworker’shealtharemediatedthroughcognitiveandpsycho-physiologicalpathways.Thus,thereductionofonlyphysicalloadatworkdoesnot,therefore,automaticallyresultinthereductionofmusculoskeletalsymptomsanddisability.Theneedforinfluencingsimultaneouslyonbothphysicalandpsychosocialexposurehasbeenseenasthemoreeffectiveapproachtothereductionofdis-ability(Coteetal.2008),preferablyincollaborationwiththeworkers(Hignettetal.2005).
8.1.2. factors associated with perceived disability
TheresultsofstudyIIindicatedthatperceivedpartialdisabilityiscom-mon,especiallyinmentalproblemsandMSD.Thesetwodisordersarealsomostoftenregardedaswork-relatedbythepatientsandtheirphysicians.MSDandmentaldisordersassuch,aswellasperceivedwork-relatednessofthehealthproblem,arestronglyassociatedwithimpairmentinself-assessedworkability(studyquestionNoII).
Accordingtothepatients,74 %ofMSDcasesweredefinitelyorpossiblycausedormadeworsebywork,whereasOHphysiciansfounddefinitework-relatednessinonly22 %andapossibleconnectionin34 %ofthecases.ThesefiguresarecomparabletotheresultsofaNor-wegianstudy,wherepainintheneck,shoulderandarmwasconsideredasbeingwork-relatedby78–80 %ofthesubjects(Mehlumetal.2009).Inthatstudy,thephysiciansusedspecificcriteriaforwork-relatedness,andtheyassessedwork-relatednessas"probably","possibly"and"notwork-related".Thesedifferencesexplainwhyinthepresentstudythephysicians'assessmentswerelowerthantheexperts'assessmentsintheNorwegianstudy(56 %versus65–72 %).Moreover,intheNorwegianstudy,thephysicianknewthestudysubject’sassessmentbeforemakinghis/herownevaluation.
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Anotherstudyhascomparedtheassessmentsofwork-relatednessmadebypatientsonsickleaveascomparedwiththeassessmentbytheirOHphysicians(Girietal.2009).Onceagain,thepatientsmoreoftenbelievedthattheillnesshasbeencausedbyworkthanOHphysi-cians(30 %versus16 %),andthattheillnesswasmadeworsebywork(60 %versus44 %).InadditiontoMSDandotherillnesses,37 %ofthepatientshadamentalproblemasthereasonforabsence,whichmayhaveinfluencedthepatients'assessmentsofwork-relatednessoftheirailments.
Thisstudyshowedthatthepatients'negativeperceptionsabouttheirillnessandworkwouldbeassociatedwithimpairedabilitytowork.Thiswasacross-sectionalstudyand,therefore,itisnotknownifthepatientswereabsentfromworkbecauseoftheillnessaftertheconsulta-tion.However,laterstudieshavefoundevidencethatemployeeswithnegativeperceptionsabouttheirillnessarelesslikelytoreturntoworkthanthosewithpositivebeliefs(Elferingetal.2009;Girietal.2009)
Thisstudyrevealedthattheriskofperceiveddisabilitywaslowerifthepatientfoundbenefitsinpotentialwork-relatedinterventions.Inapreviousstudy(Tellnesetal.1990),apotentialforpreventionwasfoundin37 %ofthehealthproblemsunderlyingsicknesscertificates.Inthisstudy,work-relatedinterventionswereinitiatedexactlyasoftenasinanotherFinnishstudy,where9 %ofthevisitstoOHphysiciansincludedorledtowork-relatedinterventions(Räsänenetal.1997).Thereasonforthisfigurebeingconsiderablylowerthantheprevalenceofwork-relateddiseasesmaybethatwork-relatedinterventionshavebeeninitiatedalreadyduringearliervisitstotheOHphysician.
Basedontheresults,partialabilityofanemployeetoworkcanpos-siblyberestored,maintainedandpromotedbyactionsdirectedattheindividual,butitshouldalsoincludemodifyingtheworkenvironmentandorganizingworkaccordingtotheindividual’scapabilities.Inaddi-tion,recognitionofwork-relateddiseasesisimportantfortheappropriateassessmentofpatient'sill-healthandfortheeffectivenessoftherapeuticinterventions.Identifyingwork-relatednesshasthepotentialalsoformoreadequateprevention,notonlyconcerningtheindividualpatientsbutalsotheirco-workers,andforlessabsenteeismfromwork.
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8.1.3. Productivity loss as an indicator of disability
InstudyIII,morethanhalfofthesubjectswithclinicallydiagnosedUEDreportedthatthedisorderimpairedtheirproductivityinvariousphysicalaswellassedentaryoccupations(studyquestionIII).Onaverage,work-erswithUEDreportedthatonethirdoftheirregularproductivityhasbeenlost,whichinanormalworkdaywouldcorrespondto2.5hoursofactiveworkingtime.
Ourresultsareconsistentwithcurrentknowledge,i.e.,painin-tensity,paininterferencewithwork,andliftingatworkareassociatedwithself-reportedproductivityloss(Hagbergetal.2007;Boströmetal.2008).Nostudieshavesofarreportedabouttheroleoffear-avoidancebeliefsinproductivityloss.Conceptually,fearfulbeliefsmaycontrib-uteconsiderablytoproductivitylosssincetheyserveasanadaptivereactiontopainwithsomeworkactivitiesbeingavoidediftheyareanticipatedtoproducepainandfearedsincetheycancause'damage'.BeliefsthatworkdeteriorateschronicLBPhavebeenshowntoincreasetheriskofbothworklossanddisabilityindailyactivities(Waddelletal.1993).Ingeneral,fear-avoidancebeliefsarestrongpredictorsoffuturedisability(Ilesetal.2008).However,itseemsthatthisisthefirststudytoreportfear-avoidancebeliefsaffectingproductivitylossinnon-chronicconditions.
Unlikethepreviousstudies,noassociationwasfoundbetweenageandproductivityloss(Collinsetal.2005;vandenHeuveletal.2007;Alaviniaetal.2009).However,itwasfoundthatagemodifiedtheeffectsofotherfactors,particularlythecombinedeffectsofphysicalwork,jobstrainandpainintensity,onproductivityloss.Thestrongestdeterminantsofproductivitylossinyoungerworkerswerehavingtwoofthefollowingfactors;intensivepain,highjobstrain,andphysicalwork.Olderwork-ers'productivitywasnotaffectedbythecombinationofthesefactors.
Similarresults,indicatingthattheyoungerworkersmaybemoresusceptibletotheeffectsofwork,havebeenfoundforexampleinaprospectivestudyonthepredictorsoflow-backpain(Mirandaetal.2008),aswellasinrelationtosicknessabsence(Taimelaetal.2007).Theage-modificationinproductivitylossmaypartlybeexplainedbyhealth-basedselectioninwhichworkerswithhealthproblemsaremorelikelytoleaveajob.Otherpossibleexplanationsareyoungeremployees'(ortheir
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supervisors’)higherexpectationsfordailyperformance,aswellasolderworkers'betterskillstocompensateforhealth-relatedproductivityloss.
8.1.4. Secondary prevention of disability
TheresultsofstudyIVshowthatanearlyergonomicinterventioninadditiontomedicalcarecanhelptoreducework–relatedproductivitylossassociatedwithUEDcomparedtomedicalcareonly(studyquestionIV).Thefactthatthedifferencebetweenthecontrolandinterventiongroupwaslargestat12weeksaftertheenrolment,suggeststhattheresultisbasedonactualimpactoftheinterventionratherthanonthesubjects'satisfactionwiththeadditionalattentiontheyhadreceivedfromtheOHS.Manyofthenewaidsortoolsrecommendedbytheoccupationalphysiotherapistswerenotpurchaseduntillaterduringthecourseofthestudy.Thismayfurtherexplainwhythedifferencebetweenthestudygroupswasfoundonlyat12weeks.
Onepossibleexplanationfortheimprovedproductivityisthattheinterventionmanagedtomodifytheemployees'adverseworkstyles,whichhasbeenshowntobeariskfactorforupperextremitypainandfunctionallimitations(Nicholasetal.2005;Meijeretal.2008).Thecon-tactsbythephysicianandthephysiotherapistmightalsohavepromotedabetterunderstandingofthenatureandconsequencesofthedisorderattheworkplace.Consequently,theemployeeandthesupervisorwereabletoadjusttheworkrequirementstobettermeettherestrictionsduringrecoveryandthenthephysiotherapist'spracticalsuggestionssupportedtheimplementationofthesechanges.
Althoughtheinterventionshowedbeneficialeffectsonproductivity,nodifferenceinpainintensitywasfoundbetweenthegroupsat12weeks.Therefore,painreliefdoesnotexplaintheresults.Sincethedifferenceinproductivityat12weekswasseenalsointhesubgroupwithnosick-nessabsenceduringthefollow-up,theresultscannotalsobeduetotheinterveningimpactofsicknessabsenteeism.
Asubstantialeffectoftheinterventionwasseenamongthoseem-ployeeswithnooronlymildproductivitylossatbaseline.Theothersubgroupanalysesshowedthatthosewithlessfear-avoidancebeliefs,morephysicalloadfactorsatwork,orlowjobdemandsbenefittedmorefromtheintervention.Thissuggeststhattheimpactoftheintervention
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onproductivitycouldbemediatedbyareductioninphysicalloadfactors.Iftheconditioncausedmorefunctionalimpairment(productivitylosswasmorethan20 %atbaselineortherewasprevioussickleaveduetoUED),itwasfoundthattheinterventionwasnoteffective.WhenthedisabilitycausedbyUEDwastoosevere,itseemsthatergonomicinter-ventionshavelesspotentialforrestoringnormalperformanceatwork.
8.1.5. Comparison of two disability management methods
ThetargetofthisprotocolwastodescribeaRCTwithastudyinterven-tionofadjustingwork(bothworktimeanddemands)toaccommodatethedisabledemployeesothatheorshewouldbeabletocontinueworkingduringrecoveryfromaMSD(studyquestionNoV).ThisisbelievedtobethefirstRCTtoinvestigatetheeffectivenessofearlypart-timesickleaveincomparisontoconventionalfull-timesickleaveinmusculoskeletalsymptoms.TheresultsandtheincreasedknowledgewillleadtoabetterdecisionmakingprocessregardingthemanagementofdisabilityrelatedtoMSD.
Despitethefactthatpart-timesicknessabsencehasbeenmadepossibleinmanyjurisdictions,thisoptionhasnotbeenstudiedinarandomisedcontrolledsetting(Kaustoetal.2008).Inaddition,there-sultsofstudyIIshowthatmorethaneveryfourthemployeecomingtomedicalconsultationbecauseofMSDreportedthattheywerepartiallyabletocontinueworkingdespitethedisorder(table8).
Aspointedoutearlier(Durandetal.2007),inthistypeofinterven-tionworkbecomesanobjectoftheinterventionitselfposingseveralmethodologicalchallenges.Inadditiontothemedicaljudgementbythephysician,theinterventionrequiresactionsanddecisionsmadebytheemployee,supervisor,colleaguesandemployer–eachwiththeirownvalues,objectives,interests,andtraining(Loiseletal.2005).
Sicknessabsenceisusuallyconsideredasaconsequenceofahealthdisorderratherthanitstreatmentand,therefore,inmoststudies,ithasbeenusedasanoutcomemeasure.Inthistrial,however,themodeofsickleave(part-orfull-time)isusedasaninterventiontoaffecttheoutcome,i.e.,thequantityofsickleave(cumulativenumberofsickleavedays).Thepotentialbenefitoftheintervention,i.e.,thedifferenceinthetotal
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numberoffull-orpart-timesickleavedaysbetweentheinterventionandcontrolgroups,willmostlybeattributedtotheneedforeitheradditionalpart-orfull-timesickleaveduringthefollow-upperiod.
8.2. Methodological considerations
8.2.1. Study designs
Thestrengthofthiscombinationofstudiesisthattheyfollowthecourseofdisability(figure4)recognisingthefourpotentialstepsintheinterven-tions.Thestudiesrepresentsystematicreview,surveys(bothcross-sectionalquestionnaireandbaselineassessment),andrandomisedcontrolledtrials.
Systematic review
ThestrengthofthereviewisthatitadheredtothesystematicandrigorousCochranemethodsinsearchingtheliterature,selectingtheinterventionsandstudydesigns,aswellassynthesisingthedata.
Themeasurementoftheoutcomesintheprimarystudiesvariedleadingtoconsiderabledifferencesinthereportedincidencesofbackpain.Anotherlimitationwasthatalltherequireddatacouldnotbeextractedfromallstudies,limitingthepossibilitiesofpoolingthedata.Inaddition,theresultsofmostofthestudieshadtobeadjustedfortheeffectofclusterrandomisationthathadnotbeentakenintoaccountbytheoriginalauthors.
ItisnotpossibletoexcludethepossibilitythatthestudiesandthereviewlackedthepowertodetectasmallbutpossiblyrelevantdifferenceintheincidenceofLBP.Itis,however,highlyunlikelythatpoolingtheresultsofmorestudieswouldhavefoundasignificantbeneficialeffect.ThisisbecausealmostallstudiesshowedanORthatwasnearto1,andtheappliedcomparisonswereallrathersimilar,especiallyastheuseofalumbarsupportcanbeconsideredequaltonointerventionwithrespecttothepreventionofbackpain(Jellemaetal.2001).Onlyonestudyshowedamorepositive,butstillnon-significant,outcome(Yassietal.2001).Thiscouldbebecausethetypeoftheinterventionwasdifferent(“nostrenuouslifting”).
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Surveys
InstudyII,onemayquestionwhetherthepatientswerecompetenttoassesstheworkrelatednessoftheirsymptoms.Itcanbearguedthatthepatient'sassessmentisbasedmoreonillness-relatedproblemsatworkratherthanonoccupationalcontributorsoftheillness,leadingtoover-reportingofwork-relatedness.Differentperceptionsofwork-relatednessbypatientsandtheirphysicianshavebeenregardedasacriticalpointofaneffectiveconsultationprocess(Plomp1993).Theworkers'confidenceintheOHphysicianisalsobasedontheirassessmentsofthephysician'smedicalexpertiseandhis/herunderstandingoftheworkersandtheirproblems(Plomp1992).Inthisstudy,however,thevalidityofpatients'assessmentsofwork-relatednessissupportedbythesimilaroccupationalexposuresreportedbythepatientsandtheirphysicians.
Onepotentialsourceofsystematicerrorinthetwosurveysisthesocalled"commonsourcebias".Whenboththeoutcome(perceiveddisabilityorself-assessedproductivityloss)andthestudyvariables(forexample,work-relatednessofthedisorderorfear-avoidancebeliefs)areinquiredfromtheemployee,thismightleadtoacommonsourcebias(Podsakoffetal.2003).Peoplerespondingtoquestionsposedbyresearch-erscanhaveadesiretoappearconsistentandrationalintheirresponsesandmightsearchforsimilaritiesinthequestionsbeingaskedofthem.However,resultssimilartothosedescribedinstudyIIandIIIhavebeenreportedalsoinotherstudiesusingmoreobjectivedatasources.
Incontrasttopreviousstudies,theincludedsubjectsinstudiesIII–IVwereexaminedbyatrainedphysicianusingstandardizeddiagnosticcri-teria.Onthewhole,validatedquestionswereusedtocollectinformationonseveralbackgroundvariables.However,unmeasuredconfoundingforexampleduetonon-occupationalormotivationalissuesmayhaveaffectedtheresults.
Thedifficultyinquantifyingproductivity,particularlyininforma-tionandservice-typeoccupations,hasledtoamultitudeofmeasure-mentinstrumentsbasedonself-reporting.TheQQmethodbyBrouwerwasadaptedbyspecifyingittoconcernUED,evenifitwasoriginallydesignedtobeusedforanydisease.ThestrengthoftheQQmethodisthattheeffectofthehealthconditiononthequantityandthequalityofproductivitycanbedifferentiated.Moreover,unlikethesituation
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withmanyotherquestionnaires,thereisareferenceagainstwhichthelosscanbecompared,i.e.,therespondentsareaskedtoratetheattainedquantityandqualityofdailyworkcomparedtothatoftheirregularworkday.Naturally,thereareotherreasonsforlostproductivitythatarenotrelatedtohealth.However,theQQmethodtakesintoaccounttheseotherreasonsforproductionlossbyusingtheregularworkperformanceasaninternalstandard.
Moreover,theself-assessmentswereunlikelytohavebeenaffectedbyrecallproblemssincetherecallperiodofproductivitywasshortinthisstudy.Formostemployees,theprecedingfullregularworkingdaywasthedaybeforetheconsultationoratmostitwaswithinoneweek.Theshorttimeframealsomeansthattheproductivitylossassessedinthisstudydidnotnecessarilyreflectlongerlastingproductivityloss.ConsideringthenatureofclinicalUED,itis,however,unlikelythatthesituationwouldchangerapidlyfromonedaytothenext.
Randomised controlled trials
Therandomisedcontrolleddesignisconsideredastheleastsusceptibletobiasinscientificinterventionresearch.InstudyIV,theinterventionandcontrolgroupswerecomparablewithoutanymajordifferencesotherthantheinterventionitself.Theergonomicinterventionreachedalmostallsubjectsintheinterventiongroupandmorethan400improvementswereproposed.
Liftingatworkandspecificshoulderdisorderswere,however,some-whatmoreprevalentinthecontrolgroup,whereastheproportionofelevatedscoresinfear-avoidancebeliefswashigherintheinterventiongroup.Thesubgroupanalysesinthisstudyshowedthatthoseemployeeswhowereexposedtolifting,forcefulgrippingorelevatedarmposturesorwhohadlessfear-avoidancebeliefsbenefittedfromtheinterventionmorethanthosewhohadlessphysicalexposuresatworkormorefear-avoidancebeliefs.Therefore,thesedifferencesatbaselinemighthavedilutedthebenefitsoftheintervention.Anotherfactthatmighthavehadasimilareffectontheresultsisthemethodtoreplaceproductivitydataat12weekswiththevaluesat8weekswhichhadtobedonefor8subjectsintheinterventiongroup;thismayhaveoverestimatedtheremainingproductivitylossat12weeks.
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Sincetherearenoobjectivemeasuresforproductivityinmostoccupa-tions,thegenerallyacceptedmethodistouseself-assessedproductivityaswasdoneinthisstudy.Inpreviousinterventionstudiesamongem-ployeeswithsymptomsintheupperextremitiesandneckregion,bothobjectiveandself-assessedproductivityhavebeenmeasured(vandenHeuveletal.2003;Rempeletal.2006).Incomparisontothesestudies,theweaknessofthispresentstudyisthatthatnoobjectivemeasurementofproductivitycouldbeused,whereasthestrengthisthatthedisordersweremedicallyverifiedusingstandardizeddiagnosticcriteria.
InstudyVcomparingtheeffectsofpart-andfull-timesicknessabsence,itisessentialthatthephysiciandeterminesthelengthofthedisabilitybeforeallocation,andadherestothisevaluationwhenprescribingeitherpart-orfull-timesickleave.Thisistoavoidbiasthatmightoccurifthelengthofthesickleaveisdetermineddifferentlyforpart-andfull-timesickleave.Thereisariskforbiasrelatedtothepossiblecontrolvisit,duringwhichtheallocationtofurtherpart-orfull-timesickleaveisagainopentoboththephysicianandtheemployee.Inadditiontorecurrenceofsickleave,aninappropriatelytimedreturntoregularworkineithergroupcouldbeanticipatedtoresultinsecondaryoutcomes,suchaspain,functionalstatus,employeesatisfactionandfinancialcoststotheemployer.
Despitetheextensiveamountofquantitativedatacollectedinthistrialonindividual,ergonomic,psychosocialandeconomicfactors,itisnotpossibletoquantifyalltheaspectsofthearrangementsmadeattheworkplacesduringpart-timesickleave.Acknowledgingthepotentialeffectofthiscontextualprocessontheoutcomeoftheintervention,allrelevantqualitativedatawillbecollectedduringthestudyfromtheemployeeandthesupervisor.
8.2.2. Study populations
Thestudieshaveincludedonlyworkingindividualsrepresentingawiderangeofemployeesinseveraloccupations.StudiesII–Vincludedonlyworkerswhosemusculoskeletalsymptomswereverifiedbyaphysician,whereasself-reportedLBPwasregisteredinstudyI.
Thereview(studyI)includedstudieswithemployeesexposedtoheavyliftingatwork.Theoriginalaimwastoincludeonlypreventionstudieswithworkerswithoutbackpainatbaseline.However,intheeli-
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giblestudiestherewerealwayssomeworkersalreadysufferingfrombackpainatbaseline.Therefore,thisinclusioncriterionhadtobechangedtoworkerswhowerenotactivelyseekingtreatmentforcurrentbackpain.
ThepreviouslyreportedprevalencesandmagnitudesofproductivitylossassociatedwithMSDhavebeenlowerthanthatestimatedinstudyIII(Hagbergetal.2002;vandenHeuveletal.2007).Themainreasonmaybethatthepreviousstudieshaveincludedsubjectswithself-reportedsymptoms,whereasinthisstudy,subjectswiththesymptomshadsoughtmedicaladvice,andformostofthem,thephysiciandiagnosedaspecificUED.Hence,theirconditionwasmoresevereandspecificthansimplyanexperienceofpain.
ThesubjectsinstudiesIIIandIVwereactivelyworkingindividualsfromthreecompanieswithvaryingexposuretowork-relatedfactors.Theseindividualswereseekingmedicaladvicefortheirupperextremitysymptoms.Theintendednumberofstudysubjectswasnotgathered.Duetotherelativelysmallpopulation,theresultsarenotveryprecise,asindicatedbythewidthoftheconfidenceintervalsinstudyIII,andthereweresomebaselinedifferencesinstudyIV.However,despitethelimitedstudysize,theresultssupportthepositiveeffectsofanearlyergonomicintervention.
TheparticipationrateinstudyIVcanbeconsideredashigh(88 %)duringthe12weeks’follow-up.However,duetotheincompletein-formation atbaselineandlosstofollow-up,someselectionmayhaveoccurred.Itwasanalyzedwhetherthoseindividualslosttofollow-upallocatedinitiallytointerventionorcontrolgroupdifferedwithrespecttobaselinevariables.Theconclusionwasthatthedrop-outs andthosewithincompletedata inthe interventiongroup reported ahigher exposuretoliftingandhadhigherlevelsofpainintensityandpaininterferencewithwork,leisuretimeandsleepthanthoseinthecontrolgroup.Ontheotherhand, lessproductivitylossandfear-avoidancebeliefswerereportedbythedrop-outsinitiallyintheinterventiongroup.Ifaselec-tionbiasduetonon-participationhadaffectedtheseresults,itseems,however,unlikelythatitcausedanysignificantoverestimationintheobservedimpactoftheintervention.
TheOHSstaffswererequestedtorecommendstudyparticipationtoallpotentiallyeligiblesubjects,butthereisnoinformationaboutwhetherthiswasthecase.Furthermore,itisnotknownhowmanysubjectsde-
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clinedtoparticipate.ItistruethatafterbeingexaminedattheFIOH,nonedeclined.Thiswasoriginallyanergonomicinterventionstudy,anditcouldbethatthoseindividualswithmoreseveresymptoms(andlowerproductivity)werelesslikelytoparticipate.
8.3. Implications for future research
Thescopeofthethesisisverywide,andthereforeitspotentialtoad-equatelyanswerallstudyquestionsissomewhatlimited.Muchresearchhastobeperformedinthefuture,beforeasignificantlybetterunder-standingaboutMSD,disabilityandworkwillbeachieved.
ThesystematicreviewonLBPandliftingadvicerevealedthatthereisaneedformoreandbetterqualityresearchwithstandardisedoutcomemeasurement,appropriatepower,andadjustmentfortheclustereffect.Suchstudiesshouldbedirectedata“noliftingpolicy”.Inadditionabetterunderstandingisneededofthecausalchainbetweenexposuretobiomechanicalstressorsatworkandthesubsequentdevelopmentofbackpaintoenablethedevelopmentofnewandinnovativewaystopreventbackpain.
SincemostoftheemployeesinstudiesonUEDandassociatedproductivitylosswerefemaleandworkinginahealthcareorofficeenvironment,thegeneralisationoftheresultsoftheinterventionhastobesomewhatlimited.MoreresearchisneededonproductivitylossandMSDinotherworkenvironments,suchasheavyindustry.
AstheinterventioninstudyIVhadtwoparts,telephonecon-tactwiththesupervisorbythephysicianandworkplacevisitbythephysiotherapist,itisimpossibletodifferentiatewhethertheybothwerecrucialfortheeffectorifone(andwhich)wouldsuffice.Therefore,moreresearchisneededfortoclarifywhichwerethecrucialpartsoftheintervention,butalsoinordertoverifytheresultsindifferentoc-cupationalsettings.
OnecanalwayscriticizethattheresultsofstudiesII–VperformedintheFinnishOHSmaynotbevalidandapplicableinothercountrieswithadifferentkindofsocialsecurityandOHSsystem.Thisisajus-tifiablecriticism,becauseasignificantamountofstudiesonMSDanddisabilityhavebeenperformedincountrieswherethejurisdictionsmake
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adistinctionbetweenwork-relatedMSDandotherMSD.Itisclearthatallsocialsecuritysystemsprobablyhavesomeeffectoninterven-tionsaimedatdisabilitymanagement,butthisshouldnotdiscourageresearchespeciallytryingtotranslatesuccessfulmodelsinonecountryforimplementationinanother.
8.4. Policy implications and recommendations
ThestudiesofthisthesiswereperformedinFinland,withtheexceptionofthestudiesincludedinthesystematicreview(studyI).Inaddition,mostofthestudiesareresultsofcollaborationbetweenFIOHandOHSunits.Therefore,theresultsareapplicabletotheFinnishsocialsecurityandOHcaresystem,andsomeconclusionsaswellasrecommendationscanbemadebasedonthefindings.
Inadditiontopreventiveservices,theFinnishOHScanalsoofferprimaryhealthcarelevelcurativeservicestotheemployees.Thisofferspossibilitiesforbettermanagementofemployeeswithdisabilitiesinadditiontoearlierrecognitionofhealthandsafetyrisksatworkduringmedicalconsultations.Asinhealthcareingeneral,itcanbearguedthatthedisabilitymanagementbyOHphysicianshasbeenmainlybasedonthebiomedicalmodelwithtoolittleemphasisplacedonassociatedwork-related,psychosocialandpsychologicalfactors(fordetailsseechapter2.2.).
TheactivitiesoftheOHSpersonnelshouldbedirectedmoretowardsdisabilitymanagementinordertomeetthedemandsoftheorganisationsandsocietyonOHS.In2005,tertiarydisabilitymanagementservicestoenableandsupportsafeRTWwereavailableinlessthanhalfoftheFinnishOHunits(Kivistöetal.2008).Thecontentsoftheserviceswerebasedonthecurrentscientificevidence,butwithsubstantialvariation.
Theresultsofthisthesischallengethebiomedicalmodelofdisabilitypreventionandmanagement.TheadaptationofbiopsychosocialmodelinthedisabilitymanagementcreatesneedsfortrainingofbothOHSpersonnelandtheworkplaces,aswellasfinancialincentivesfortheem-ployerstoappreciatethevalueandtosupporttheretentionofemployeeswithdisabilities.Whennomedicalcureisattainable,theindividual's
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potentialscanbeidentifiedandsupportedinordertoenablehisorhersuccessfulreturntothemodifiedwork.
MSDaremultifactorialintheirnature,andtherefore,apartfromac-cidentprevention,theirelimination (primaryprevention)bythemeansofwork-relatedinterventionsisnotrealistic.Thereismoreevidenceavailable,towhichthisstudyadds,thatrecognitionofMSDshouldleadtoearlyanalysisofboththework-relatedconsequencesandtheem-ployee'sownperceptionsconcerningthedisorder.InsteadofkeepingtheemployeeoutofworkbecauseofMSD,workactivitiescanbemodifiedandthenegativeconsequencesofthedisorderminimised.
MostcasesofLBPandmanyofUEDarenon-specific,andtheso-called“objective”measuresofpathologyhavebeenpoorinpredictingdisability.Thereisconvincingevidencethatsecondaryandtertiarypre-ventionofdisabilityiseffectiveif,afteradequatemedicalassessment,thebiopsychosocialaspectsofthedisorderandrelateddisabilityaretakenintocarefulconsideration.Workplace,supervisorandcolleaguesshouldbeincludedinthemanagementofdisabilityatanearlierstageifthedisabilityislikelytobeprolonged.AsinstudiesIV–V,thisnecessitatescollaborationandcommunicationnotonlybetweenthecareproviderandtheemployee,butalsoattheworkplacewiththesupervisorandthecolleagues.Thisapproachmostlikelyleadstostrongerinvolvementandgreaterinterestamongsupervisorsinimprovingtheworkenviron-mentandsupporttheemployeewithMSD.Asaconsequence,withanimprovementofthesupervisor'sroleandknowledgerelatedtoMSD,theresultscanbenefitalsoallemployees,withorwithoutsymptoms.
Basedonthefindingsofthisstudythefollowingrecommendationscanbemade
1. Themethodsusedforprimarypreventionofwork-relatedMSDshouldbescrutinised.Inthosecaseswheretheireffectivenessisnotsupportedbyscientificevidence,theresourcesbeingallocatedtothemshouldbedirectedtomoreeffectivemethods.Healthprofessionalsinvolvedintrainingandadvisingworkersonmanualmaterialhan-dlingshouldmodifythecontentssothatnosingleliftingtechniqueisadvocatedforliftingandhandling.Instead,theaimshouldbetoreduceliftinginthefirstplace,andtopreventworkaccidentsrelatedtohandlingheavyobjects.
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2. Thebenefitsofprimary,secondaryandtertiarypreventionofdisabilityaresupportedbycredibleevidence.PreventionofMSDatworkisdif-ficultbecauseoftheirhighprevalenceandcomplexaetiology.However,thereareevidence-basedmethodswhichareabletopreventtherelateddisability.InthesurveillanceofMSDintheOHS,theemployees'ownperceptionsofworkingconditionsandtheireffectsonmusculoskeletalhealthshouldbeusedinsteadofsimplyrelyingonexperts'assessments.
3. Inthesecondarypreventionofdisability,lostproductivityatworkduetoMSDshouldbetakenintoconsideration.ThisisimportantwhensupportingworkerswithMSDincontinuingworking,andwhenundertakingeconomicevaluationsoftheconsequencesofdisabilityatworkandoftheinterventionstoreducethem.Oftensicknessabsenteeism,painorfunctionalstatusmightbetooinsensi-tiveasoutcomestodetectpossiblebenefitsofinterventions.
4. Aprerequisiteforsecondarypreventionofdisabilityisbetterknowl-edgeanduseofalternativemodelsofthebiomedicalapproach.AtOHS,moreeffortsshouldbeplacedonearlyergonomicinterventionsinvolvingboththeemployeesandtheirsupervisorsinsteadofwastingtoomuchtimeinpurelymedicalinterventions.Inthisapproach,thebiopsychosocialmodelofdisabilitymanagementismorelikelytobenefittheemployeethanthebiomedicalmodel.
5. Whenassessingtheworkabilityoftheemployeeandhis/herneedforsickleave,attentionshouldbepaidnotonlytothemedicalcon-ditionbutalsotothepsychosocialandpsychologicalriskfactorsofthedisability.Thisispivotalforrecommendingtheuseofpart-timesickleaveormodifiedworkinsteadoftraditionalsickleaveinthemanagementofMSD.
8.5. Conclusions
ThefivestudiesofthisthesisaimedatansweringfivequestionsrelatedtoMSD,disabilityandwork.• TheresultsofstudyI,asystematicliteraturereview,donotsupport
theuseoftraininginliftingtechniqueswithorwithoutassistivedevicesasawayofpreventingLBPandrelateddisabilityamongworkersfrequentlyexposedtoheavylifting.
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• AccordingtostudyII,MSDareresponsiblemoreoftenforself-assessedpartialworkabilitythanfullinabilitytowork,andworkersmoreoftenthantheirphysiciansassessmanyofthehealthproblemsasbeingcausedorexacerbatedbywork.Self-assessedwork-relatednessofthedisorderisassociatedwithperceiveddisability.
• InstudyIII,workerswhodidnotneedsicknessabsencenonethelessassessedUEDtocausemajorproductivitylossatwork.
• InstudyIV,themanagementofUEDrelatedproductivitylossshowedthatearlyergonomicinterventionattheworkplaceissuperiortomedicalcareonly.
• ThechallengeofdesigninganRCTtostudytheeffectivenessofpart-timesickleaveamongworkerswithMSDwasapproachedintheprotocoldevised instudyV.
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ORIgINAL PUBLICATIONS I–v
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Cover picture: Sami Rantanen
Musculoskeletal disorders, disability and work
People and WorkResearch Reports 89
Kari-Pekka Martimo
Musculoskeletal disorders, disability and w
orkK
ari-Pekka Martim
oMusculoskeletal disorders (MSD) are the most important causes of temporary and permanent work disability. The aim of this thesis was to examine the role of work in the disability caused by MSD from various perspectives: primary prevention using lifting advice and devices, perception of work-relatedness, measurement of productivity loss, and secondary/tertiary prevention through ergonomic intervention or part-time sick leave. The original articles include a systematic review, two surveys, a randomised controlled trial, and a study protocol. The results support the early use of a biopsychosocial model for effective management of disability.
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