prevalence of symptoms of knee or hip joints in older adults from the general population

Aging Clin Exp Res, Vol. 20, No. 4 329

Key words: Functional limitation, hip, knee, pain, prevalence, questionnaires.Correspondence: José Mª Quintana, MD, Unidad de Investigación, Hospital Galdakao-Usansolo, Barrio Labeaga s/n, 48960Galdakao, Vizcaya, Spain.E-mail: [email protected] April 17, 2007; accepted in revised form August 17, 2007.

Prevalence of symptoms of knee or hip joints in olderadults from the general population

Aging Clinical and Experimental Research

José Mª Quintana1, Antonio Escobar2, Inmaculada Arostegui3, Amaia Bilbao4, Pedro Armendariz5,Iratxe Lafuente1, and Urko Agirre11Unidad de Investigación, Hospital de Galdakao-Usansolo, CIBER Epidemiología y Salud Pública(CIBERESP), Galdakao, Vizcaya, 2Unidad de Investigación, Hospital de Basurto, CIBERESP, Bilbao, Vizcaya,3Departamento de Matemática Aplicada, Estadística e Investigación Operativa, CIBERESP, Universidad delPaís Vasco, Leioa, Vizcaya, 4Fundación Vasca de Innovación e Investigación Sanitarias (BIOEF), CIBERESP,Sondika, Vizcaya, 5Servicio de Traumatología, Hospital de Cruces, Baracaldo, Vizcaya, Spain

ABSTRACT. Background and aims: The prevalence ofknee and hip symptoms varies from study to study, or isunknown. The goals of this study were to determinethe prevalence of these symptoms, of diagnosed os-teoarthritis and the use of prostheses, by age and gender,in a sample of the general older population. Methods:We mailed a questionnaire to 11,002 people aged 60 to90 years who were selected by stratified random sam-pling. The questionnaire included questions on pain,functional limitations, diagnosed osteoarthritis, previ-ous operations on either or both joints, and sociode-mographic data. Descriptive statistics were performed. Re-sults: From 10,150 people who fulfilled the selection cri-teria, 74.6% answered the questionnaire. Up to 49.2%of the subjects reported pain in either knee or hip or both,with pain in the knee reported more frequently (38.3%)than the hip (23.8%). Functional limitations were presentin 51.6% of respondents, with 42.5% having limita-tions in the knees and 27.7% in the hips. The symptomsincreased with age and were more prevalent in women.About 6.6% of respondents reported that they had al-ready had prosthesis implant (hip 3.9%; knee 2.6%). Thepresence of a hip prosthesis was slightly lower in womenthan in men and more women had a knee prosthesis.Physicians had already diagnosed osteoarthritis in 38.5%of the sample, 19.4% of the hip and 31% of the knee.Conclusions: The prevalence of pain symptoms is rela-tively high among older people, more often in the kneeand, in both joints, more often in women, but the rate ofprosthetic surgeries was low, which means that addi-tional studies are necessary to gain insight into thehealthcare needs of the population.(Aging Clin Exp Res 2008; 20: 329-336)©2008, Editrice Kurtis

INTRODUCTIONPain in the large joints of the human body is com-

mon, especially in older adults, and is more frequent inhip or knee joints (1). Symptomatic hips or knees causeconsiderable disability and social isolation in elderly in-dividuals (2). Chronic hip and knee pain in older adultsis primarily due to osteoarthritis, a diagnosis that isfrequently made solely on clinical grounds, due to thelack of agreement between the signs of osteoarthritis andsymptoms (3). For severe symptoms of osteoarthritis,joint replacement is the treatment of choice, and hip andknee procedures are both considered to be similarlyeffective (4).

Several studies have reported the prevalence of hip orknee pain in adult populations, but with diverse results(2, 5-8). Despite the age range of the patients in thosestudies, all agree that the prevalence of hip or knee dis-ease is highest among those who are over 65 years ofage. While published reports on population-based stud-ies have tended to concentrate on either the hip orthe knee, rarely have both been studied together inany detail. Knee pain is more prevalent than hip pain(9), although in Spain, as elsewhere in Europe, the in-cidence of primary hip arthroplasty is considerablyhigher than knee arthroplasty, leading to the suspicionthat individuals with knee pain in our countries may haveunmet healthcare needs. Determining a population’sneed for healthcare intervention is an enormously dif-ficult challenge. However, without attempts to quantifyhealthcare needs, proper health service planning is un-feasible (10).

To determine the prevalence of hip or knee symptoms,we conducted a survey of individuals aged 60 and over inthe general population of our province.

titionsonsinincrcreerrA

ReeR --eeeelectiectionn crcrii--

aire.aire. UpUp toto 49.2%49.2%either knneeee oror hihippii oror bothboth,

reporportedted morer freequequentlynt (38.323.8%%).). FFuuFFF ncnctionational llimiim tations

6%% ooffoo rerespsponondendentsts,, withwit 442 5s inin thethe kneekneess andnd 27.7%2asesedd wiwithth agea and66.6%6 fh

cnn eldeerlyrly

painn iinn ololdederr aduaduthritis, aa didiaagnosgnosiiss ththaatt

lelyely onon clilinicanicall grgroundsounds, dued tment bettwewet eenn tthee ssiignsgns ofof oste

ptoms (33)).. ForFo seververee ssymy ptomjoiintnt repeplaclacemenementt is the treatkknneeee pprorocedce ures aeeffeectivecti (4)

Se

sennttviingng llimiimitata--

iippii s.s. TheThe symptsymptomsommormoreerrr pprrevaevarrr llenentt iinn

ndendentnts repoeportr eded thathattheshesiiss iimplmplantant (hipp( 3hiphip prprostheostherrr siandan

stestecchoichoice,e, ana

conconsidersidereded toto beb

ddieess hhavavee rereportertedd thpain inin adaduultlt popoppulaula

((2,2, 5-5-88). Deespspiitet thhsstutudiedies,s, ala leeaa

METHODSThis project was conducted from April 2002 to De-

cember 2003 in the province of Vizcaya (Basque Coun-try) in northern Spain. Vizcaya, a predominantly urban re-gion with some rural areas, has a population of1,125,000, and 23.6% of residents were over 59 atthe time of the study.

This study is part of a larger project than consists oftwo phases: in the first phase, the survey was sent to allindividuals who fulfilled the selection criteria for screeningto determine who had symptoms suggestive of os-teoarthritis of hip or knee; in the second phase, those in-dividuals with symptoms suggestive of osteoarthritis ofknee or hip were invited for a more thorough explo-ration carried out by experienced orthopedic surgeons.The results reported in the current manuscript refer ex-clusively to the first phase of the project.

RECRUITMENTTo recruit people from the general population, we

used the registry of the Basque Department of Health,which includes all individuals covered by the NationalHealth System, which in the Basque Country coversalmost 100% of the population. From that registry, weperformed stratified random sampling by gender andage in three age groups (60-69, 70-79, and 80-90 yrs)of all adults in Vizcaya.

Considering the prevalences of 10% for knee os-teoarthritis and 5% for hip osteoarthritis in previous stud-ies of patients over 59 (5, 6, 11-14), of 10% for knee os-teoarthritis and 5% for hip osteoarthritis, and for α=0.05,1-β=0.8, and an error in the prevalence of osteoarthritis of±1.0%, we estimated that we would need to recruit about7200 people in order to study both joints. We estimated anexclusion rate of less than 10% from the initial sample and

a participation rate of at least 70%. Therefore, we neededto include at least 11,000 people in the study.

The inclusion criteria were age older than 59 years, res-idence in Vizcaya, and ability to complete the question-naire and provide consent to participate in the study. Thefollowing individuals were excluded: those under 60;those not resident in the province; those with an erro-neous mailing address not corrected by contacting themby phone; those who had died at the moment of the be-ginning of the study or during it; those with severe psy-chiatric, sensorial or physical illness; and those with lan-guage problems which prevented them from completingthe questionnaire.

Question developmentBefore the study, we developed a questionnaire to

study the prevalence of symptoms of osteoarthritis. First,we reviewed the literature at the beginning of 2002 toknow previous studies (6, 11-13, 15). We then selected thevariables that were more likely to identify patients with kneeor hip osteoarthritis, based on the questions and results ofthe studies mentioned above, and considered the experi-ence of our team of orthopedic surgeons. The question-naire had 28 questions in three sections: 11 questions re-lated to hip symptoms, OA diagnosis or surgery, 11 toknee symptoms, and 6 general questions.

Data collectionWe sent a letter to 11,002 patients to invite them to

participate in the study. The packet included: a presen-tation letter in which the study goals were described; a re-quest for patients’ informed consent; the questionnaire onknee and hip osteoarthritis; and a stamped return enve-lope. A reminder letter was sent to all people who had notreplied after 15 days. We sent the questionnaire again to

J.M. Quintana, A. Escobar, I. Arostegui, et al.

330 Aging Clin Exp Res, Vol. 20, No. 4

Fig. 1 - Patient recruitment process: number of patients excluded and included from original sample.

People selected:total sample n = 11,002

Recruitment process

10,150 Included

2573 Non-respondent7577 Answers

852 Excluded

- Address unknown, absent: 499- Death: 135- Lives outside our area: 42- Severe physical or mental disease: 123- Not able to fill in questionnaire: 17- Too young <60 years: 8- Over 80 years with severe mobility problems (not able to attend consult): 28

- Questionnaire not returned: 2326- Refused to answer: 177- Data from other person: 70

±1.±1.0077220000e

yrsyrs))

1010%% fforr knkneee osos-oarthritistis inin pprevirevioousus ststudud-

(5,, 66,, 111-14), of 10%10% fforo kneek5% forfor hih pp osteosteoaoarthrirth tis, and f

8,, andd aann ererrorror inin thehe prevapre lencelen0%,%, wewe estestimatematedd ththat we0 ppeopeoplele inin orderor toioonn rate of

sselectedtedcy ppaatietieaa nntstsnn withwith knkn

the queuestistionsons anndd resesultsults oababovove, anandd cconsions deredered theth ex

am of oorthorthopepedicdic susurgrgeoneo s. Thad 28 qquueests ionss inin tthrhreeee section

latteded too hihipp ssymympptoms, OAO dikknneeee symsympptotommss, and 6

Data

055,,oarthritisoarthritis ofof

eeedd ttoo recrecruitruit aboutabouootthh jojoinintstsnnn .. WeWe estestimatima

ann 10%10 fromfrom tthehe initiiniti

ququs oror surgesurg

alal ququesesttionions.s.

iiononsentt aa letletterter toto 1111 0

parpa ttiiccipate inin tthhettatationion letlettteqquue

FO

those who had not replied after another 15 days, and fi-nally contacted the others by phone.

Of the 11,002 people randomly selected, 852 were ex-cluded. Of the 10,150 finally included in the study, 2326 didnot return the questionnaire after three mailings and tele-phone contact, 177 refused to participate, and for 70 theinformation was provided by another relative, resulting in a74.65% participation rate. The recruitment process, withreasons for exclusion, is shown in Figure 1. Table 1 showsthe percentage of non responders and those excluded byage and gender. The study was approved by the researchcommittee of our hospital. All data remained confidential.

Statistical analysisFrequencies and percentages were calculated as de-

scriptive statistics of the sample for categorical variables;

means and standard deviations were calculated for age withthe same purpose. Hip and knee osteoarthritis were treat-ed separately. The prevalence data of the symptoms stud-ied referred to pain, limitation or stiffness, “occurring onmost days for 1 month or longer during the 12 months be-fore the completion of the questionnaire,” as performed inprevious studies (6, 11, 15). To assess the association be-tween categorical variables, Chi-square tests were per-formed, with Fisher’s exact method for counts of lessthan five. We included 95% confidence intervals (95% CI)or an estimate of the difference between groups with a95% confidence interval (95% CIp1 − p2, where p1= preva-lence in men; p2= prevalence in women) for the main glob-al comparisons made among gender prevalences.

All effects were considered significant at p<0.05, un-less otherwise noted. The main statistical analyses were

Knee or hip joint symptoms in older adults


Gender Total Excluded Non-responders Responders p-value*Total (No.) 11,002 852 (7.7) 2573 (23.4) 7577 (68.9)

Male <0.001<70 2410 (49.3) 207 (49.2) 468 (40.8) 1735 (52.4)70-79 1902 (39.0) 140 (33.2) 504 (43.9) 1258 (38.0)80-90 569 (11.7) 74 (17.6) 175 (15.3) 320 (9.6)

Total 4881 (44.4) 421 (49.4) 1147 (44.6) 3313 (43.7)

Female <0.001<70 2623 (42.8) 123 (28.5) 505 (35.4) 1995 (46.8)70-79 2372 (38.8) 158 (36.7) 586 (41.1) 1628 (38.2)80-90 1126 (18.4) 150 (34.8) 335 (23.5) 641 (15.0)

Total 6121 (55.6) 431 (50.6) 1426 (55.4) 4264 (56.3)

*p-value indicates comparison between responders and non-responders to questionnaire columns, by gender.

Table 1 - Recruitment of patients, classified by age and gender.

Parameter Item Total Hip Kneeresponse n n (%) n (%) n (%)

Age �– (SD) 70.96 (7.0)<70 3730 (49.2)70-79 2886 (38.1)≥80 961 (12.7)

GenderMale 3313 (43.7)Female 4264 (56.3)

Physician-diagnosed OA* 7268 2800 (38.5) 1398 (18.4) 2275 (31)History of fracture* 6668 521 (7.8) 191 (2.5) 354 (4.7)History of joint prosthesis* 7096 466 (6.6) 296 (3.9) 195 (2.6)History of other operation(s)* 7105 608 (8.6) 130 (1.7) 494 (6.5)Presence of pain* 7086 3490 (49.3) 1801 (23.8) 2900 (38.3)Presence of stiffness* 7200 2023 (28.1) 933 (12.3) 1633 (21.6)Presence of functional limitation on* 7377 3775 (51.6) 2098 (27.7) 3218 (42.5)Rising from a chair* 7083 1554 (20.5) 2157 (28.5)Walking (>4 blocks)* 7035 1352 (17.8) 1902 (25.1)Ascending steps* 7220 --- 2614 (34.5)Descending steps* 7208 --- 2608 (34.4)Putting on socks, stockings or shoes* 7111 1689 (22.3) ---

*Percentages were calculated based on available answers. OA: osteoarthritis.

Table 2 - Descriptive data for patients and joints (n=7577).TTablb

bybye resre earchearch

ainaineded coonnfidfideenntitial.a

andd percenpercentagestage wwere calculatstatitiststiicscs ofof thethe samampplele foorr cat

mpmptomss ssnessss,, “o“occuccurringrring

ger durinngg tthehe 1212 monthmonthss bbtthhee quequeststionionnnaiaire,re ” asas perfperformed

s (6, 111,, 115)5).. Too assasseessss theth ascategooririccala variiabablles,es, CChhii-squ

forormem d,d, wwiti hh FiFishsher’s eexacttthhaann fivvee.. WeWe ininccludl ed 9oor aann estitimate995% cl

2 -- DescDescriptiv

dee--ll varivariablableses;;

ssffoorr ccououn

onfio dencdencee iintentervrvalavvv sdiffedi rencencee betwbetweenee

ce inintervalterval (95%(95% CICImeen;n; pp22== prprevevaavvv lelenn

aall coommparissonsons maddAAllll eefffef ct

llesse

OR PFO

patiepatientsnts aandnd jojointsints (

performed with SAS for Windows statistical software,version 8.2 (SAS Institute, Inc., Cary, NC).

RESULTSThe exclusion rate, although less than 8%, increased

with participants’ age. The number of non-responders al-so increased with age, especially among those 80 yearsand older, but no differences between genders werefound (p=0.5) (Table 1, Fig. 1). The participation rate was74.65%.

The mean age of the responders was about 71 years,and 56.3% were women. Most reported functional limi-tations (51.2%) in either or both joints, 42.5% in kneesand 27.7% in either hip. Pain was reported by 49.3%(95% CI 48.1-50.4) of people, knee pain in 38.3%(95% CI 37.2-39.4), and hip pain in 23.8% (95% CI22.8-24.7). Stiffness was a common symptom of the knee(21.6%) (95% CI 20.6-22.5), but was less common in thehip (12.3%) (95% CI 11.6-13.1). The most commonlimitations reported for knee joints were ascending or de-scending steps (34.5% each) and putting on socks, stock-ings or shoes for the hip joints (22.3%). Of the respon-ders, 38.5% (95% CI 37.4-39.6) reported that they hadreceived a diagnosis of osteoarthritis, 31% of the knee(95% CI 30.2-32.4) and 18.4% (95% CI 17.6-19.3) in ei-ther hip joint. Lastly, more prostheses were reported tohave been implanted in hips (3.9%) (95% CI 3.5-4.9) thanknees (2.6%) (95% CI 2.2-3.0), whereas there weremore operations and fractures of the knee joints (Table 2).

Regarding the hip joint, 31.0% of women and 19.4% ofmen reported hip pain, a difference (-11.5; 95% CIp1 − p2:-13.6, -9.5) that reached significance (p<0.001) (Table 3).Of those who reported hip pain, 75.1% (95% CI 71.4-78.6) of men and 78.8% (95% CI 76.3-81.0) (p=0.1) ofwomen reported that it interfered with walking; the rateswere higher in those aged 80 to 90. Of those who re-ported pain, more women (59.3%) frequently took med-ication to control pain than men (44.5%) (p<0.001).More women (34.1%) than men (23%) reported limita-tions, a difference (-11.1; 95% CIp1 − p2: -13.2, -9.1) thatreached significance (p<0.001). The most frequently re-ported limitations by both men and women were puttingon socks, stockings or shoes, although this was more fre-quently reported by women. There were differences bygender (men= 14.7%; women= 23.1%; p1 - p2= -8.4;95% CIp1 − p2: -10.2, -6.6) when participants were askedif they had already been diagnosed with hip osteoarthri-tis by their physicians, differences that remained in all agegroups. However, the percentages of those who had aprosthesis differed only between men (3.0%) (95% CI 2.3-3.9) and women (1.8%) (95% CI 1.34-2.4) (p=0.02) inthe 60-69-year-old age group. In addition, their physiciansindicated the need for future hip operations in about3.8% of men and 3.4% of women, a difference that didnot reach significance (p=0.4) (Table 3). The percentage



60-69(n=3730)

70-79(n=2886)

80-90(n=961)

Men

Wom

enMen

Wom

enMen

Wom

enQue

stions

n(n=1735)(n=1995)

p-value

(n=1258)(n=1628)

p-value

(n=320)

(n=641)

p-value

Duringthelast12

months,have

youfrequentlyhadpain

ineitherhipfor1monthor

more?

6945

19.2

31.1

<0.001

20.8

32.3

<0.001

15.6

26.9

0.0002

Ifso,istheremorepainwhenwalking?

1693

74.5

77.3

0.4

74.8

79.8

0.1

81.4

80.7

0.9

Ifpain,didyoutake

medicationfrequently?

1730

43.8

57.8

0.001

43.2

63.4

<0.001

55.6

51.4

0.7

Hasadoctor

everdiagnosedOAineitherhip?

7204

13.5

21.3

<0.001

16.3

25.3

<0.001

15.1

23.0

0.01

Haveyoueverhadaprostheticoperationon

eitherhip?

7232

3.0

1.8

0.02

4.8

4.9

0.9

10.2

7.8

0.2

Haveyouhadanyothersurgicaloperationon

eitherhip?

7218

1.4

1.1

0.3

1.6

2.3

0.2

3.9

3.5

0.7

Duringthelast12

months,have

youhadfrequentstiffness

ineitherhipfor1monthor

more?

7176

10.4

14.5

0.0002

10.1

16.2

<0.001

10.9

14.3

0.2

Duringthelast12

months,have

youhadanyofthefollowing

limitations

becauseofpainor

stiffnessineitherhip?

7179

20.8

32.5

<0.001

24.9

35.6

<0.001

28.0

35.4

0.03

Risingfrom

achairor

toilet

7093

15.5

24.9

<0.001

17.2

27.7

<0.001

20.6

25.7

0.1

Puttingon

socks,stockingsor

shoes

7111

17.5

25.2

<0.001

20.7

29.1

<0.001

22.0

29.9

0.01

Walking

4blocks(or500meters)

7078

12.5

21.5

<0.001

14.1

24.7

<0.001

17.6

26.4

0.003

Hasaphysicianevermentionedafuturehipoperation?

6535

3.9

2.7

0.05

3.8

4.0

0.9

3.1

4.3

0.4

Haveyoueverhadahipfracture?

6668

2.2

1.7

0.4

1.9

3.3

0.04

6.2

7.4

0.5

Haveyoueverhadpainor

aphysiciandiagnosedOA?

6869

9.5

16.2

<0.001

11.6

19.1

<0.001

10.1

15.5

0.03


functionallimitations?

6837

14.8

25.3

<0.001

17.5

26.4

<0.001

14.1

23.0

0.002

OA:osteoarthritis.

Table3-Self-reportedhipsymptom

sandmedicalhistoryofgeneralpopulationover59

byageandgender(%).

OfOf tt778.68.6w

toto.5-4.9)4.9) thanthan

ereereasas therehere wewererf the kneenee jojointin ss (T(Taabblle 2).2)

ntn ,, 31.31.0%0 of wommenen andand 1199 4%p ppain,ain, aa ddiffeiffererencence (-11.5;5 95%

9.5) thatthat rreaceachheded sigsignifnificanicanccee (hhososee whwhoo repreportrteded hip pai)) ofof menmen andand 78 8%nn repore rtedi

ri=33773300))

en

c95))

pp--vvalu

<<00..00001

00..44

0.001

<0.0011

0.0022

0.3 00

0022 0124

117

1220.

1144..11 33.88

11..99

1111..66

1177..55s

er5599

bbyyagg c

1 − pp22::1)1) (Table(Table 3).3).

1%% (95%(95% CICI 71.71.4-4CCII 776.36.3-81-81.0).0) ((pp(( 0

ininteterferreded wiwithth walkwalkthothosese agedaged 808 ttoo 9

mmoorere womenwomen (5(5ntntror l

A 6600--66

nnW U

335)(n= 3311 7777

..5577.8

2211.33 11.88

1.1

44..55 55

<< << <<00

<00. 00..00

044

ppuullaattiioo L

of those reporting hip fractures increased after 80 yearsof age in both genders.

Regarding the knee, 46.6% of women reported pain,more frequently than men (32.4%) (-14.2; 95% CIp1 − p2:-16.5, -12.0) (p<0.001). Of those who reported pain,women took medication (61.0%) (95% CI 58.7-63.2)more frequently than men (44.1%) (95% CI 41.0-47.2)(p<0.001). At the same time, women reported morelimitations, especially ascending (42.4%) (95% CI 40.9-44.0) and descending steps (42.9%) (95% CI 41.4-44.4),whereas in men both limitations were also the most fre-quently reported but less often than in women (ascendingsteps: 28.3%; 95% CI 26.8-29.9; descending steps:27.6%; 95% CI 26.1-29.2) (p<0.001 among genders forboth limitations). Women had been diagnosed with os-teoarthritis in the knees more frequently by their physi-cians (37.5%) compared with 22.7% of men (-14.8;95% CIp1 − p2: -16.9, -12.8) (p<0.0001). In addition,there were differences between men (1.6%) and women(3.5%) who had knee prostheses (-1.9; 95% CIp1 − p2: -2.6,-1.2) (p<0.001). Among people in all age groups whowere informed by their physicians of the future need fora knee operation there were more women (10.4%) thanmen (6.3%) (-4.1; 95% CIp1 − p2: -5.4, -2.7) (p=0.0002).Knee fractures declined for men as they aged. For wom-en the percentages remained stable (Table 4).

Table 5 shows the number of patients with symp-toms in both joints at the same time or in either. In eitheror both joints, from 58.5% to 53.7% of women, de-pending on age, reported pain and a higher percentageof functional limitations. From 35.8% to 41.7% of menreported pain, and more than 40% reported functionallimitations. Pain was present in both joints simultaneously,the percentage decreasing as age increased in both gen-ders. The presence of any functional limitation increasedin men as they aged, whereas women aged 70 to 79years had more frequent functional limitations (27%).From 12% to 15% of women and 4.6% to 10.6% of menreported that their physicians indicated the need for a fu-ture operation in one of those joints. A prosthesis had al-ready been implanted in either knee joint in 3.6% ofthose between 60 to 70 years, and in 12.7% of womenfrom 80 to 90 years and 3.8% and 13% of men, re-spectively. Taking medication frequently to control painin either hip or knee joints was reported by 76.7% to90% of responders who reported pain, with higher per-centages for women.

DISCUSSIONThe current study of a large sample of elderly subjects

from the general population highlights various importantissues. First, the prevalence of hip or knee symptoms wasslightly higher than in some studies performed in devel-oped countries, mainly in Europe (2, 3, 5, 16, 17). Sec-ond, as in most previous studies, women always had a



60-69(n=3730)

70-79(n=2886)

80-90(n=961)

Men

Wom

enMen

Wom

enMen

Wom

enQue

stions

n(n=1735)(n=1995)

p-value

(n=1258)(n=1628)

p-value

(n=320)

(n=641)

p-value

Duringthelast12

months,have

youfrequentlyhad

painineitherknee

for1monthor

more?

7190

32.3

46.1

<0.001

33.5

48.0

<0.001

28.2

44.4

<0.001

Ifpain,didyoutake


2793

41.0

55.1

<0.001

46.8

67.1

<0.001

50.6

63.8

0.04

Hasadoctor

everdiagnosedOAineitherknee?

7346

21.3

33.8

<0.001

24.7

41.6

<0.001

22.1

38.5

<0.001

Haveyoueverhadaprostheticoperationineitherknee?

7355

0.8

1.8

0.02

2.2

4.8

0.003

3.2

5.6

0.12

Haveyoueverhadanyothersurgicaloperationineitherknee?

7374

8.6

6.9

0.06

6.6

6.0

0.5

3.3

4.3

0.5

Duringthelast12

months,have

youhadfrequentstiffness

ineitherknee

for1monthor

more?

7342

17.0

23.9

<0.001

18.5

28.7

<0.001

14.6

26.4

<0.001

Duringthelast12

months,have

youhadanyofthefollowing

limitations

becauseofpainor

stiffnessineitherknee?

7333

34.3

49.1

<0.001

36.7

52.1

<0.001

37.1

50.7

<0.001

Risingfrom

achair

7168

22.0

34.3

<0.001

22.4

37.3

<0.001

26.3

38.3

0.0003

Ascending

steps

7220

26.9

40.3

<0.001

29.7

44.2

<0.001

30.7

44.7

<0.001

Descendingsteps

7208

26.4

40.6

<0.001

29.2

45.2

<0.001

28.2

44.1

<0.001

Walking


7139

18.8

28.3

<0.001

21.1

33.6

<0.001

24.3

38.2

<0.001

Duringthelast12

months,have

youfrequentlyhadany

feelingofknee

insecurityor

haseitherknee

failed?

7149

24.1

36.1

<0.001

24.5

39.9

<0.001

29.3

38.5

0.01

Hasaphysicianevermentionedafutureknee

operation?

6535

7.3

9.5

0.03

6.1

12.1

<0.001

1.9

9.0

0.0002

Haveyoueverhadaknee

fracture?

6668

7.1

5.7

0.1

4.0

4.6

0.5

1.8

4.8

0.04


aphysiciandiagnosedOA?

7105

17.5

29.4

<0.001

21.0

36.6

<0.001

17.5

33.4

<0.001


anyfunctionallimitations?

7088

27.8

41.7

<0.001

29.1

44.1

<0.001

25.1

40.7

<0.001

OA:osteoarthritis.K

neefracture:D

istalfem

oralfracture,patellarfractureor

othertype

ofknee

fractures.

Table4-Self-reportedkneesymptom

sandmedicalhistoryofgeneralpopulationover59

byageandgender(%).

lilimimitttthehe ppded

withh syympmp--inin eeithither.er. IInn eieiththere

o 53.7%% ooff wwomen,omen, dede-rtedd papainin and a highhigheerr pep rcent

mitaations.tions FrFromom 3535.8%. to 41.7d pain,ain, andand momorere ththanan 40%0%

attiions.ons. PainPain waw ss prepresent in berercentagcentagee ddecreaThThee pres

rin=33773300))

men

c95))

pp--vvalu

<<00..00001

<<00..00001

<<00.0001

0.02

0.0066

0.00011

0011

0011

201

2901

291

221.

2244.55 66..11

44.00

2211..00

2299..11s

oveerr5599

bbya

icmenen

ffuunctnctionalionaloino ttss sisimumultltaneouslaneouslyylll

aggee iincncrreeaasesedd inin bothbotannyy ffuncctitionalonal llimitatimita

yy aged,ged, whwhereaser wworeore ffrequrequentnt ff1155% ff

A 6600--66

nnW U

3355)(n= 4466 5555 3333

..8 11..88

66..99

23.9 99..11 33 33

<6

<< <<00

<<00.0

00.00

ooppuullaatt L

higher prevalence of joint symptoms, although the preva-lence of implantation of prostheses was lower than inneighboring countries. In addition, as in previous studies,knee symptoms were more prevalent than hip symp-toms, but, so far, the rate of implantation of knee pros-theses has been far lower than hip prostheses.

To our knowledge, only one study conducted in the UKin 2002 reported prevalence rates for hip and knee painsimultaneously in a sample of 5500 people over 65,with a 66.3% response rate (2). Those investigators usedthe Short Form-36 to capture overall health status,whereas in this study we did not. However, we collecteddata on some functional limitations reported by patients,whereas those researchers did not. A comparison of theresults of both studies indicated that the men in our sam-ple reported a slightly higher prevalence of pain in bothjoints; in the case of women, our results were higher thanin the UK. The use of a prosthesis was slightly lower forhips and similar to that for knees, although there were dif-ferences in very elderly women, in whom the percentagewas 18% in the UK study and 8% in the present study.

Other studies have evaluated hip and knee symptomsbut reported the results separately. Two studies con-ducted in the UK provided additional data for comparison(12, 13). Again, the prevalence of reported implantationsof hip prostheses performed in the present study washigher for men but similar for women. However, thewomen in our sample reported a higher prevalence ofpain. Another study (13) provided information about theneed for knee prostheses ranging from 13 to 35 per1000 cases, but it was conducted in the early 1990s.

Studies performed in the UK (6, 11) with 26,046participants reported knee pain in 21.4%, with a higherprevalence in women (23.6%) and in those over 84(37.8%). In the case of hip pain, the global prevalence was14.3%, which was greater in women (17.3%) than in men(10.7%), increased with age, and reached its highestrate in individuals over 74 (>19%). In a study conductedin Framingham, MA, US (15) (parts of which we used toconstruct our questionnaire), having a sample of 2318people and a wider age range than our study, the preva-lence of knee pain was about 18.4%.

Other studies, performed mainly in the UK from the1990s to the present, evaluated the presence of knee painin various samples from the general population and foundhighly diverse prevalences of this symptom (18-24). The re-sults of previous studies varied from a 12-month prevalenceof knee pain of 46.8% in one study (22), and 49% in an-other (24), to prevalence of pain of more than 3 monthsduration in 25.3% (22), and 28.7% (19), and a prevalenceof 18-19% in others (18, 23). Some studies did not reportdifferences in the prevalence of pain between men andwomen (19). Some reported prevalences of symptoms inthe knee joint (between 35.4 to 37.7%, depending on age)and in the hip (25.6% to 28.3%) (20, 21). These results



60-69

70-79

80-90

H+K

H/K

H+K

H/K

H+K

H/K

Que

stions

Men

Wom

enMen

Wom

enMen

Wom

enMen

Wom

enMen

Wom

enMen

Wom

en

Duringthelast12

months,have

youhadpain

inhips/knees

for1monthor

more?

12.3

21.8

39.5

55.6

12.9

21.7

41.7

58.5

8.4

17.7

35.8

53.7

Ifpain,didyoutake


15.4

27.7

76.7

86.3

17.5

35.4

77.9

90.0

13.6

27.2

86.6

86.9

Duringthelast12

months,have

youhadfrequent

stiffnessinyourhips/kneesfor1monthor

more?

6.0

8.0

21.6

30.6

5.7

9.9

23.2

35.2

5.1

7.7

20.7

33.2

Duringthelast12

months,have

youhadany

ofthefollowinglim

itations

becauseofpainor

stiffnessinanyknees/hips?

14.6

24.8

40.7

56.6

16.9

27.1

44.5

60.3

17.2

26.4

47.9

59.1

Risingfrom

achairor

toilet

9.7

16.4

28.1

42.9

10.0

18.6

29.9

46.5

12.2

17.5

34.9

46.3

Walking


8.6

14.2

23.0

35.8

8.6

16.9

26.9

41.6

11.5

18.5

30.8

46.2

Has

adoctor

everdiagnosedOAinyourhip/knee?

7.7

13.2

27.3

42.0

9.2

16.7

32.0

50.3

9.1

15.4

28.3

46.4

Has

aphysicianevermentionedafuture

hip/knee

operation?

0.7

0.5

10.6

11.7

0.5

1.2

9.4

14.8

0.4

1.3

4.6

12.1

Haveyoueverhadahip/knee

fracture?

0.1

0.3

9.2

7.2

0.4

0.6

5.6

7.4

0.0

1.1

8.0

11.2

Haveyoueverhadaprosthesisoperation

onhip/knee?

0.1

0.1

3.8

3.6

0.4

0.5

6.7

9.5

0.6

1.0

12.9

12.7

Haveyoueverhadanyotherjointoperation?

0.1

0.1

10.2

8.1

0.3

0.4

8.2

8.1

0.0

0.3

7.4

7.8

OA:osteoarthritis.H

+K:hipandknee

symptom

s;H/K

:hipor

knee

symptom

s.

Table5-Self-reportedhipand/orkneesymptom

sandmedicalhistoryofparticipantsbyageandgender(%).

© 6

hhiissttoorryy

eerer werereeomm thethe percpercentaenta

d 8% inn tthehe prpresentsent studstudyevaluatevaluateded hhiipp anand knkneeee sympt

he resusulltsts sesepaaratratelely.y TwT oin the UKUK provideidedd addiadd tiional d

(122,, 133).). AgaAgaiin,n, ththe prevalenooff hhiipp pprroosts hehesesse pe fhih gheherr ffor mwwome

2600--6699

K

0

ommeenn

M

83399

.57

7766..77

2211..66

4400..77

288.11

42233..00

327.3

42

0.6

1111..77

277.22

33..66

88.11 it

ccepporteortedd iimpm

ini tthhee ppreseresenntt simiim lar forfor wwoomenmen

ssaampmplele repre ortrtededAnoththerer studystudy (1(133))

nneedeed for knkneeee pr10100000 ccasa e

SS

22.33

5.44 0

88 24.88

1166.44

1144..22

133..22 0.55 33

1100ON

must be considered carefully, since study methods, time-frames, and the range of ages in the selected popula-tions and the objectives all differed. In addition, in the US,some population studies focused on symptoms in theknee (25) as well as in the hip (7). In one populationstudy (25), the rates of knee pain ranged from 18.1% inmen and 23.5% in women, and increased with age.

In most cases, the sample population in the presentstudy reported a higher rate of knee or hip pain than inprevious studies. As some reviews have shown (e.g. 5), theprevalence of symptoms is related to the types of ques-tions included in the questionnaire. In that review, theprevalence of knee pain in different studies in the UK var-ied from 6.5% to 28% depending on how questionsabout knee pain were phrased.

Convergely, it is important to note that a high per-centage of subjects who reported pain were frequently tak-ing medications to control it, and that percentages in-creased with age and gender, i.e., individuals aged 80 andolder and women. These factors should have an additionalnegative impact on the health of those individuals.

We used questions similar to those in previous studies(6, 11-13, 15), since most of them had been conductedbefore ours and we based the development of our ques-tionnaire partly on them. In addition, the method ofconducting the survey, i.e., the use of a mailed ques-tionnaire, was in most cases similar to ours. Therefore, webelieve that the results of our study are comparable to pre-vious studies, although there are differences among themin the age range of the population, sample size and re-sponse rate, length and type of questions, and the fact thatour study was performed later than the previous ones.

Although the information contained in this manuscriptis extremely basic for health service planning in our area,our results do provide epidemiologic information on acommon symptomatology from specific age groupswhich, if combined adequately, can provide more credibleestimates of health service needs. The estimation of in-dividuals who would require treatment for osteoarthritis(drugs or surgery) is beyond the scope of this article, butsome authors have already proposed validated tools to de-termine which cases would be considered appropriate fora hip or knee prosthesis (4, 12, 13, 26, 27). The infor-mation included in this manuscript is a first step toward es-timating the health service needs related to these patholo-gies in our area, and is similar to that of other authors (6,11-13). Unfortunately, in many places this elementary in-formation is not available.

Our responders reported having had hip implants,which also included those due to fractures, or knee pros-theses at a lower rate, especially for the knees, and few-er women had had implants. These factors are espe-cially important, since those were the groups with thehigher prevalence of symptoms. Compared with other Eu-ropean countries (2, 28), such as the UK, where several

studies similar to ours and with more complex method-ology have been carried out, our rate of implantation ofprostheses seems to be lower, and is still lower when wecompare Spain with countries such as the US (29, 30).This probably shows that we have still not reached our po-tential for prosthesis implantation, especially in the caseof knees and, therefore, that all essential health needshave not yet been met. The Spanish Health Service,which is public and covers almost 100% of the population,as in the UK or other European countries, is quite differentto that of the US. This may explain some of the differ-ences among studies. However, more complex analysesare needed to reach a definite conclusion.

This study has some limitations. First, we did not askour responders to identify which side, or joint, of the kneeor hip was symptomatic. We tried to develop a short ques-tionnaire to ensure a high response rate, so we did not in-clude those questions, and may therefore have underes-timated the prevalence of joint problems. Second, al-though we tried to have representative sample sizes by ageand gender, our final sample size for individuals over79 was smaller than the other age ranges, especially formen, for whom the non response rate was higher. We donot have complete information, except for age and gen-der characteristics, about the non responders, and there-fore cannot form a precise judgment about the directionof any bias. The response rate was about 75%, smallerthan in some previous studies, but higher than in others.Although based on questions developed previously byother researchers, our questionnaire has not been vali-dated. In order to make the questionnaire short, we onlyincluded basic sociodemographic questions. Lastly, asreported previously (5), the type of questions included mayhave affected the final results, a factor that we did notstudy. However, we used methodology similar to previousstudies of high scientific quality.

CONCLUSIONSOur study indicates, like previous studies in neighbor-

ing countries, that the prevalence of knee and hip pain isrelatively high among older people, more often in theknee, and in both joints more often in women than inmen. However, comparison with other studies showsan important disparity in the prevalence rates, probablynot explainable by population differences. This is proba-bly due to the use of different types of questionnaires, aswell as to the definition of the time-frame symptom usedin the various studies. For this reason, we recommend uni-fying and standardizing the type of questions in a well-structured and validated questionnaire that can be trans-lated into various languages and used in many countriesin order to carry out epidemiologic studies allowing inter-regional or inter-country comparison of results.

The prevalence of pain symptoms was high, and therate of prosthetic surgery low, which means that additional



AAisis exexto

ess-ereforefore,e, wewe

compcompaarababllee ttoo prpree-e differencenceses amoamongng tthehem

ppooppululation, sammpleple sizs e andngth aandnd typetype ofof qquuq esestionstss , and th

yy wasas ppererfoformedrmed latlaterer thanan thAltthouhoughgh thethe infoinforrmmata ion crerememelyly bbasasicic for hessulultsts do

SSecondnd,,sampmplele ssiizeszes byby aa

p e size forfor iindividuandividualsls ovo eheh othotherer ageage ranganges,s espees ciall

m the noonn rresespponnsese rarattee was higve commplpleette inforormmatatiion,o exc

deerr chaararactcteerisristictics,s aboutt thefforeore cancannonott foformrm a poof ananyy bbiias. Thtthanh i

hatatououss ones.ones.

inn tthishis mamanunuscriptscriptrvicvicr ee pplalannnniingng inin oou

epepidemioidemiolologicgic inforinformpptomtomatoatolologygy fromommbinmbineded aadeqdequuata lhhealea th

agagsponspondersders,

udgmeudgmenntt aaboboutut ththeppononse ratratee waswas ababoo

prevpreviiououss stustudies,s bbutgh babasesedd onon qquuestes

oottherer researarcchhere sddateated.d. IInn o diinclunclu

studies are necessary to gain insight into the healthcareneeds of the population. The differences found for pros-theses indicated that there may be a severe societal orhealthcare problem that prevents women, especially old-er women, from accessing health care in the Spanishhealth system, as other researchers and we have suggestedusing qualitative methodology (31, 32).

ACKNOWLEDGEMENTSThis study was supported in part by grants from the Fondo de In-

vestigación Sanitaria (01/1619), Department of Health of the BasqueCountry and the Research Committee of Galdakao-Usansolo Hospital.Amaia Bilbao received a grant from the Department of Health of theBasque Government. We also thank the Department of Health of theBasque Government which provided some of the data necessary to per-form this study. Lastly, we thank all the individuals who generously par-ticipated in this study.

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7.7.SR

ft POP:OP: prospospeecc

anaggeemmeentnt ofo clclininicicaallpulation ofof oolderlder adaduultlts.s. BMBM

0404;; 5: 22.n K, OOnngg BN,BN CCrroftoft PP.. AA bbrier f scre

in in primary ccareare ((KKNENESSTT)). 2.2 Rethe generaall populpopu ationn agagedd 550 and2000404;; 434 :: 5555-6-611.

223.3 AdaAdamsmsoonn J, Ebrahifafactc ors forScoteoarthritishritis inin olo dd--

n andand ccurreurrentnt ususee off pripr -Dis 2001; 60:60: 9191-77..

onovovanan JJ, et al. Populatpulatiionon requiree replacementreplacement susurgery:rger a cross-s

nt].t]. RhRheueumatolmatologyogy 22003;003 42:42: 516-2ChChriristmstmass C,C CreCresspopo CCJ,J FranckSJSJ, AnAndderssenen RE.RE How coesusultslts frfromo the Thrvrvey. J F

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prevalence of symptoms of knee or hip joints in older adults from the general population

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