guides.chap 01 [001-016]final guides 5th-min.pdf · chapter 1 1 1.1 history 1.2 impairment,...

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1.1 History

1.2 Impairment, Disability, and Handicap

1.3 The Organ System and Whole BodyApproach to Impairment

1.4 Philosophy and Use of the Combined Values Chart

1.5 Incorporating Science with ClinicalJudgment

1.6 Causation, Apportionment Analysis, and Aggravation

1.7 Use of the Guides

1.8 Impairment Evaluations in Workers’Compensation

1.9 Employability Determinations

1.10 Railroad and Maritime Workers

1.11 The Physician’s Role Based on the Americans with Disabilities Act (ADA)

1.12 Summary

1.1 HistoryThe Guides was first published in book form in 1971in response to a public need for a standardized,objective approach to evaluating medical impair-ments. Sections of the first edition of the Guideswere originally published in the Journal of theAmerican Medical Association, beginning in 1958and continuing until August 1970.1 Since then, theGuides has undergone four revisions, culminating inthe current, fifth edition. The purpose of this fifthedition of the Guides is to update the diagnostic cri-teria and evaluation process used in impairmentassessment, incorporating available scientific evi-dence and prevailing medical opinion. Chapterauthors were encouraged to use the latest scientificevidence from their specialty and, where evidencewas lacking, develop a consensus view. This chapterwas revised from the earlier edition in response tospecific requests from user groups concerning thedefinitions, appropriate use, and scope of applicationof the Guides.

Philosophy, Purpose, andAppropriate Use of the Guides

Chapter 1

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The fifth edition includes most of the common con-ditions, excluding unusual cases that require individ-ual consideration. Since this edition encompasses themost current criteria and procedures for impairmentassessment, it is strongly recommended that physi-cians use this latest edition, the fifth edition, whenrating impairment.

1.2 Impairment, Disability, and Handicap

1.2a ImpairmentThe Guides continues to define impairment as “a loss, loss of use, or derangement of any bodypart, organ system, or organ function.” 2 This defi-nition of impairment is retained in this edition. Amedical impairment can develop from an illness orinjury. An impairment is considered permanent whenit has reached maximal medical improvement(MMI), meaning it is well stabilized and unlikely tochange substantially in the next year with or withoutmedical treatment. The term impairment in theGuides refers to permanent impairment, which isthe focus of the Guides.

An impairment can be manifested objectively, forexample, by a fracture, and/or subjectively, throughfatigue and pain.3 Although the Guides emphasizesobjective assessment, subjective symptoms areincluded within the diagnostic criteria. According tothe Guides, determining whether an injury or illnessresults in a permanent impairment requires a medicalassessment performed by a physician. An impair-ment may lead to functional limitations or the inabil-ity to perform activities of daily living.

Table 1-1, adapted from a report by the AMACouncil on Scientific Affairs, lists various definitionsof impairment and disability used by four mainauthorities: the AMA Guides, the World HealthOrganization, the Social Security Administration,and a state workers’ compensation statute.4 Althougha nationally accepted definition for impairment doesnot exist, the general concept of impairment is simi-lar in the definitions of most organizations. Severalterms used in the AMA definition, and their applica-tion throughout the Guides, will be discussed in thischapter and Chapter 2.

Loss, loss of use, or derangement implies a changefrom a normal or “preexisting” state. Normal is arange or zone representing healthy functioning andvaries with age, gender, and other factors such asenvironmental conditions. For example, normal heartrate varies between a child and adult and accordingto whether the person is at rest or exercising.Multiple factors need to be considered when assess-ing whether a specific or overall function is normal.A normal value can be defined from an individual orpopulation perspective.

When evaluating an individual, a physician has twooptions: consider the individual’s healthy preinjuryor preillness state or the condition of the unaffectedside as “normal” for the individual if this is known,or compare that individual to a normal value definedby population averages of healthy people. TheGuides uses both approaches. Accepted populationvalues for conditions such as extremity range-of-motion or lung function are listed in the Guides; it isrecommended that the physician use those values as detailed in the Guides when applicable. In other cir-cumstances, for instance, where population valuesare not available, the physician should use clinicaljudgment regarding normal structure and functionand estimate what is normal for the individual basedon the physician’s knowledge or estimate of the indi-vidual’s preinjury or preillness condition.

2 Guides to the Evaluation of Permanent ImpairmentC

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Philosophy, Purpose, and Appropriate Use of the Guides 3

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Guides to the Evaluationof Permanent Impairment(5th ed, 2000)

A loss, loss of use, orderangement of any bodypart, organ system, ororgan function.

An alteration of an individual’s capacity tomeet personal, social, oroccupational demandsbecause of an impairment.

Determine impairment,provide medical informa-tion to assist in disabilitydetermination.

An impaired individualmay or may not have adisability.

World HealthOrganization (WHO)(1999)

Problems in body functionor structure as a signifi-cant deviation or loss.Impairments of structurecan involve an anomaly,defect, loss, or other sig-nificant deviation in bodystructures.

Activity limitation (formerly disability) is adifficulty in the perform-ance, accomplishment, orcompletion of an activityat the level of the person.Difficulty encompasses allof the ways in which thedoing of the activity maybe affected.

Not specifically defined;assumed to be one of thedecision-makers in deter-mining disability throughimpairment assessment.

Emphasis is on the importance of functionalabilities and defining context-related activitylimitations.

Social SecurityAdministration (SSA)(1995)

An anatomical, physiolog-ical, or psychologicalabnormality that can beshown by medicallyacceptable clinical andlaboratory diagnostictechniques.

The inability to engage inany substantial, gainfulactivity by reason of anymedically determinablephysical or mental impair-ment(s), which can beexpected to result indeath or which has lastedor can be expected to lastfor a continuous period ofnot less than 12 months.

Determine impairment;may assist with the dis-ability determination as aconsultative examiner.

Physicians and nonphysi-cians need to worktogether to define situa-tional disabilities.

State Workers’Compensation Law (typical)5

“Permanent impairment”is any anatomic or func-tional loss after maximalmedical improvement hasbeen achieved and whichabnormality or loss, med-ically, is considered stableor nonprogressive at thetime of evaluation.Permanent impairment isa basic consideration inthe evaluation of perma-nent disability and is acontributing factor to, butnot necessarily an indica-tion of, the entire extentof permanent disability.(Idaho Code section 72-422)

“Temporary disability”means a decrease inwage-earning capacitydue to injury or occupa-tional disease during aperiod of recovery. (IdahoCode section 72-102[10]“Permanent disability”results when the actual orpresumed ability toengage in gainful activityis reduced or absentbecause of permanentimpairment and no funda-mental or marked changein the future can be rea-sonably expected. (IdahoCode section 72-423)

“Evaluation (rating) ofpermanent impairment” isa medical appraisal of thenature and extent of theinjury or disease as itaffects an injuredemployee’s personal effi-ciency in the activities ofdaily living, such as self-care, communication, nor-mal living postures,ambulation, elevation,traveling, and nonspecial-ized activities of bodilymembers. (Idaho Codesection 72-424)

Purpose is to provide sureand certain relief to thosewho become injured byaccident or suffer effectsof disease from exposureto hazards arising out ofand in the course ofemployment.

Table 1-1 Definitions and Interpretations of Impairment and Disability

Organization Impairment Disability Physicians’ Role Comments

Data from healthy populations, when available andwidely referenced, are incorporated into chapters ofthe Guides. In some organ or body systems, such asrespiratory, certain measurements of lung functionhave been standardized for age and gender. In otherbody systems, such as the musculoskeletal, age andgender differences are not reflected in most of thevalues. While there may be age and gender differ-ences anticipated for some musculoskeletal values,such as range of motion in the spine and extremities,this edition of the Guides mainly reflects averagerange of motion from healthy populations of mixedage and gender. The normal values presented in themusculoskeletal section are based on a review ofstudies measuring range of motion, as cited in thetext. Evaluating physicians may use their clinicaljudgment, however, and comment on any significantage or gender effect for a particular individual. Forinstance, the “normal” preinjury range of motion fora gymnast with hypermobility may exceed the listednormal values.

If an individual had previous measurements of func-tion that were below or above average populationvalues, the physician may discuss that prior valueand any subsequent loss for the individual, as well ascompare it to the population normal. For example, ahighly functioning athlete with documented, above-normal lung function, who has sustained an injuryand now has decreased lung function that is nonethe-less similar to population averages, has experienceda loss in his or her lung function and has sustained animpairment. Based only on a population comparison,the athlete would be given a 0% impairment rating.However, it would be more appropriate in thisinstance for the physician to assign an impairmentrating based on the degree of change from the ath-lete’s preinjury to postinjury state.

In evaluating impairment, the Guides considers bothanatomic and functional loss. Some chapters place agreater emphasis on either anatomic or functionalloss, depending upon common practice in that spe-cialty. Anatomic loss refers to damage to the organsystem or body structure, while functional loss refersto a change in function for the organ or body system.An example of an anatomic deviation is developmentof heart enlargement; functional loss includes a lossin ejection fraction or the ability of the heart to pumpadequately. Anatomic loss receives greater emphasisin the musculoskeletal system, as in measurementssuch as range of motion. Functional considerationsreceive greater emphasis in the mental and behav-ioral section.

The impairment criteria outlined in the Guides pro-vide a standardized method for physicians to use todetermine medical impairment. The impairment cri-teria include diagnostic criteria, incorporatinganatomic and functional measures. The impairmentcriteria were developed from scientific evidence ascited and from consensus of chapter authors or ofmedical specialty societies.

Impairment percentages or ratings developed bymedical specialists are consensus-derived estimatesthat reflect the severity of the medical condition andthe degree to which the impairment decreases anindividual’s ability to perform common activities ofdaily living (ADL), excluding work. Impairment rat-ings were designed to reflect functional limitationsand not disability. The whole person impairmentpercentages listed in the Guides estimate the impactof the impairment on the individual’s overall abilityto perform activities of daily living, excluding work,as listed in Table 1-2.


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Self-care, Urinating, defecating, brushing teeth,personal hygiene combing hair, bathing, dressing

oneself, eating

Communication Writing, typing, seeing, hearing, speaking

Physical activity Standing, sitting, reclining, walking,climbing stairs

Sensory function Hearing, seeing, tactile feeling, tasting,smelling

Nonspecialized Grasping, lifting, tactile hand activities discrimination

Travel Riding, driving, flying

Sexual function Orgasm, ejaculation, lubrication, erection

Sleep Restful, nocturnal sleep pattern

Table 1-2 Activities of Daily Living Commonly Measuredin Activities of Daily Living (ADL) andInstrumental Activities of Daily Living (IADL) Scales 6,7

Activity Example

The medical judgment used to determine the originalimpairment percentages could not account for thediversity or complexity of work but could accountfor daily activities common to most people. Work isnot included in the clinical judgment for impairmentpercentages for several reasons: (1) work involvesmany simple and complex activities; (2) work ishighly individualized, making generalizations inac-curate; (3) impairment percentages are unchangedfor stable conditions, but work and occupationschange; and (4) impairments interact with such otherfactors as the worker’s age, education, and priorwork experience to determine the extent of work dis-ability. For example, an individual who receives a30% whole person impairment due to pericardialheart disease is considered from a clinical standpointto have a 30% reduction in general functioning asrepresented by a decrease in the ability to performactivities of daily living. For individuals who work insedentary jobs, there may be no decline in their workability although their overall functioning isdecreased. Thus, a 30% impairment rating does notcorrespond to a 30% reduction in work capability.Similarly, a manual laborer with this 30% impair-ment rating due to pericardial disease may be com-pletely unable to do his or her regular job and, thus,may have a 100% work disability.

As a result, impairment ratings are not intended foruse as direct determinants of work disability. When aphysician is asked to evaluate work-related disability,it is appropriate for a physician knowledgeable aboutthe work activities of the patient to discuss the spe-cific activities the worker can and cannot do, giventhe permanent impairment.

Most impairment percentages in this fifth editionhave been retained from the fourth edition becausethere are limited scientific data to support specificchanges. It is recognized that there are limited datato support some of the previous impairment percent-ages as well. However, these ratings are currentlyaccepted and should not be changed arbitrarily. Inthis edition, some percentages have been changed forgreater scientific accuracy or to achieve consistencythroughout the book.

A 0% whole person (WP) impairment rating isassigned to an individual with an impairment if theimpairment has no significant organ or body systemfunctional consequences and does not limit the per-formance of the common activities of daily living

indicated in Table 1-2. A 90% to 100% WP impair-ment indicates a very severe organ or body systemimpairment requiring the individual to be fullydependent on others for self-care, approaching death.

The activities of daily living, as originally developedfor the Guides in the first and second editions,1,6 sig-nify common activities currently represented inscales of Activities of Daily Living and InstrumentalActivities of Daily Living.7 The Guides refers tocommon ADLs, as listed in Table 1-2. The ADLslisted in this table correspond to the activities thatphysicians should consider when establishing a per-manent impairment rating. A physician can oftenassess a person’s ability to perform ADLs based onknowledge of the patient’s medical condition andclinical judgment. When the physician is estimatinga permanent impairment rating, Table 1-2 can help todetermine how significantly the impairment impactsthese activities. Using the impairment criteria withina class and knowing the activities the individual canperform, the physician can estimate where the indi-vidual stands within that class.

There are many scales that measure ability to performADLs with greater degrees of accuracy. Many ofthese scales are concerned with more severe levels ofdisability, relevant to institutionalized patients and theelderly.7 During the 1970s, the ADL concept wasextended to consider problems experienced by thoseliving in the community, a field that has come to betermed Instrumental Activities of Daily Living(IADL).7 There is a continued effort to validate thesescales; some of the more commonly utilized, vali-dated IADL and ADL scales are listed in Table 1-3.7

Scales vary in their appropriateness for a given indi-vidual, based upon the level of impairment, body sys-tems affected, and degree of accuracy required. Somescales are most appropriate for an active, workingpopulation; others are more suited to a chronically ill,disabled population. Since there is no agreed-uponscale for a working population and physicians whouse the Guides may evaluate different populations ofindividuals (ie, healthy or chronically ill), a physicianmay choose the most appropriate of any of the vali-dated scales for a more in-depth assessment of ADL,to obtain further information to supplement clinicaljudgment, or to gain assistance in determining wherean individual stands within an impairment range.


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The OECD Long-TermDisabilityQuestionnaire 8

Summary of the impact ofill health on essentialactivities of daily living.

General population • Eyesight• Hearing• Speaking• Carry an object of 5 kg

for 10 meters• Run 100 meters• Walk 400 meters with-

out resting• Move between rooms• Get in and out of bed• Dress and undress• Cut toenails• Bend and pick up a

shoe from floor• Cut food• Bite and chew hard

food

An early attempt todevelop an internationalset of disability items;European content

The Health AssessmentQuestionnaire 9

Measures difficulty in performing activities ofdaily living

Used to assess adultarthritics in a wide rangeof research settings toevaluate care

• Dressing and grooming• Arising• Eating• Walking• Hygiene• Reach• Grip• Outdoor activity

Widely used instrument;pays close attention torigorous measures

The FunctionalIndependence Measure 10

Assesses physical and cog-nitive disability, monitorspatient progress, andassesses outcomes ofrehabilitation

General population • Self-care

• Sphincter control

• Mobility

• Locomotion

• Communication

• Social cognition

Based on the Barthelindex

Scale Design/Description Target Population Measures Comment

Table 1-3 Scales for Measurement of Instrumental Activities of Daily Living (IADL) and Activities of Daily Living (ADL)

IADL

ADLThe Barthel Index(Formerly the MarylandDisability Index) 11

Measures functional inde-pendence in personal careand mobility; completedby health professionals

Used in patients withchronic conditions, beforeand after treatment

Ten-item version evaluates:• Feeding• Moving from wheel-

chair to bed and return• Personal toilet• Getting on and off toilet• Bathing self• Mobility• Ascending and

descending stairs• Dressing• Controlling bowels• Controlling bladder

Measures what a patientdoes; widely applied

Scale Description Target Population Measures Comment


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The Index ofIndependence inActivities of DailyLiving 12

Describes primary biologi-cal and psychosocial func-tion; limited informationon ambulation

Originally developed forelderly and chronically illpatients with strokes andfractured hips

Assesses independence insix activities:• Bathing• Dressing• Toileting• Transferring from bed

to chair• Continence• Feeding

Widely used with childrenand adults, with the mentally retarded and the physically disabled, in the community andinstitutions

The Functional StatusRating System 13

Based on a method devel-oped to provide nationalstatistics on hospital uti-lization and treatmentoutcomes

Rehabilitation patients • Functional Status inSelf-Care (eating/feed-ing, personal hygiene,toileting, bathing,bowel/bladder/skinmanagement, bedactivities, dressing)

• Functional Status inMobility (transfers,wheelchair skills, ambu-lation, stairs, commu-nity mobility)

• Functional Status inCommunication (read-ing, talking, motor com-munication, writtenlanguage expression)

• Functional Status inPsychosocialAdjustment(emotional adjustment,social support, adjust-ment to limitations)

• Functional Status inCognitive Function(attention span, judg-ment, reasoning, memory)

The OARSMultidimensionalFunctional AssessmentQuestionnaire 14

A combined 7 ADL and 7IADL scale that coversfunctional and servicesassessment

General population, espe-cially elderly

• Individual functioning(basic demographics,social, economicresources)

• Mental health

• Physical health

• ADL

• Services assessment(transportation,social/recreational)

Flexible instrument, reli-able, and valid ADL andIADL sections

The Medical OutcomesStudy PhysicalFunctioning Measure 15

An extended ADL scalethat is sensitive to varia-tions at relatively high lev-els of physical function

General population • Vigorous activities (running, lifting heavyobjects, strenuoussports)

• Moderate activities(moving a table, push-ing a vacuum cleaner,bowling, playing golf)

• Lifting or carrying groceries

• Climbing several flightsof stairs

• Climbing one flight ofstairs

• Bending, kneeling, orstooping

• Walking more than onemile

• Walking several blocks• Walking one block• Bathing or dressing self

Recognizes differences inpeople’s values regardingfunctional ability byincluding a question onsatisfaction with physicalperformance

1.2b DisabilityThe term disability has historically referred to abroad category of individuals with diverse limitationsin the ability to meet social or occupational demands.However, it is more accurate to refer to the specificactivity or role the “disabled” individual is unable toperform. Several organizations are moving awayfrom the term disability and instead are referring tospecific activity limitations to encourage an emphasison the specific activities the individual can performand to identify how the environment can be altered to enable the individual to perform the activitiesassociated with various social or occupational roles.(Table 1-1).4

According to a 1997 Institute of Medicine Report,“disability is a relational outcome, reflecting theindividual’s capacity to perform a specific task oractivity, contingent on the environmental conditionsin which they are to be performed.”16 Disability iscontext-specific, not inherent in the individual, but afunction of the interaction of the individual and theenvironment.

The World Health Organization (WHO) is revising its1980 International Classification of Impairments,Disabilities and Handicaps and has released a draftdocument, The International Classification ofImpairments, Activities and Participation (ICIDH-2).17

The term disability has been replaced by a neutralterm, activity, and limits in ability are described asactivity limitations. The change in terminology arosefor several reasons: to choose terminology without anassociated stigma, to avoid labeling, and to emphasizethe person’s residual ability. Representatives world-wide are reviewing this international classificationscale of impairments, function, and activities.

The Guides continues to define disability as analteration of an individual’s capacity to meet per-sonal, social, or occupational demands or statu-tory or regulatory requirements because of animpairment.2 An individual can have a disability inperforming a specific work activity but not have adisability in any other social role.2 Physicians havethe education and training to evaluate a person’shealth status and determine the presence or absenceof an impairment. If the physician has the expertiseand is well acquainted with the individual’s activitiesand needs, the physician may also express an opinionabout the presence or absence of a specific disability.For example, an occupational medicine physicianwho understands the job requirements in a particularworkplace can provide insights on how the impair-ment could contribute to a workplace disability.

The impairment evaluation, however, is only oneaspect of disability determination. A disability deter-mination also includes information about the individ-ual’s skills, education, job history, adaptability, age,and environment requirements and modifications.3

Assessing these factors can provide a more realisticpicture of the effects of the impairment on the abilityto perform complex work and social activities. Ifadaptations can be made to the environment, theindividual may not be disabled from performing thatactivity.


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Figure 1-1 The Relationship Among the Concepts of Normal Health, Impairment, Functional Limitation, and Activity Disability (Performance Limitation)

Normal Health Impairment(loss, loss of use, derangement of body part, organ system, or organ function)

Functional Limitation(limit in the ability to perform basic activities of daily living)

Disability

No Disability

Normal Health(eg, healthy back)

Impairment(eg, disk herniation L5/S1,decreased rangeof motion)

Functional Limitation(eg, unable to lift 45 kg [100 lb])

Disability(no accomodation available; unable to work as a stock clerk)

No Disability(mechanical lift available; able to operate lift; can work as a stock clerk)

As discussed in this chapter and illustrated in Figure1-1, medical impairments are not related to disabilityin a linear fashion. An individual with a medicalimpairment can have no disability for some occupa-tions, yet be very disabled for others. For example,severe degenerative disk disease may impair thefunctioning of the spine of both a licensed practicalnurse and a bank president in a similar fashion whenperforming their activities of daily living. However,in terms of occupation, the bank president is lesslikely to be disabled by this impairment than thelicensed practical nurse. An individual who developsrheumatoid arthritis may be disabled from work as atailor but may be able to work as a child care aide. Apilot who develops a visual impairment, correctablewith glasses, may be able to perform all of his dailyactivities but is no longer able to fly a commercialplane. An individual with repeated hernias andrepairs may no longer be able to lift more than 20 kg (40 lb) but could work in a factory wheremechanical lifts are available.

The Guides is not intended to be used for direct estimates of work disability. Impairment percentagesderived according to the Guides criteria do not measure work disability. Therefore, it is inappropri-ate to use the Guides’ criteria or ratings to makedirect estimates of work disability.

1.2c HandicapHandicap is a term historically used in both a legaland a policy context to describe disability or peopleliving with disabilities. Though the term continues tobe used, generally it is being replaced with the pre-ferred term disability.

1.3 The Organ Systemand Whole BodyApproach toImpairment

The Guides impairment ratings reflect the severityand limitations of the organ/body system impairmentand resulting functional limitations. Mostorgan/body systems chapters in the Guides provideimpairment ratings that represent the extent of wholeperson impairment. In addition to listing whole per-son impairments, the musculoskeletal chapters pro-vide regional impairment ratings (eg, upper extremity,lower extremity); regional ratings are then convertedinto whole person impairment ratings. Within somemusculoskeletal regions, a consensus group devel-oped weights to reflect the relative importance of certain regions. For example, different fingers or dif-ferent areas of the spine are given different weights,representing their unique and relative importance tothe region’s overall functioning. These weights,which have gained acceptance in clinical practice,have been retained to enable regulatory authorities toconvert from a regional body to whole person impair-ment when needed.

1.4 Philosophy and Useof the CombinedValues Chart

The Combined Values Chart (p. 604) was designedto enable the physician to account for the effects ofmultiple impairments with a summary value. A stan-dard formula was used to ensure that regardless ofthe number of impairments, the summary valuewould not exceed 100% of the whole person.According to the formula listed in the combined val-ues chart, multiple impairments are combined so thatthe whole person impairment value is equal to or lessthan the sum of all the individual impairment values.


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A scientific formula has not been established to indi-cate the best way to combine multiple impairments.Given the diversity of impairments and great vari-ability inherent in combining multiple impairments,it is difficult to establish a formula that accounts forall situations. A combination of some impairmentscould decrease overall functioning more than sug-gested by just adding the impairment ratings for theseparate impairments (eg, blindness and inability touse both hands). When other multiple impairmentsare combined, a less than additive approach may bemore appropriate. States also use different tech-niques when combining impairments. Many work-ers’ compensation statutes contain provisions thatcombine impairments to produce a summary ratingthat is more than additive. Other options are to com-bine (add, subtract, or multiply) multiple impair-ments based upon the extent to which they affect anindividual’s ability to perform activities of daily liv-ing. The current edition has retained the same com-bined values chart, since it has become the standardof practice in many jurisdictions. Other approaches,when published in scientific peer-reviewed literature,will be evaluated for future editions.

In general, impairment ratings within the sameregion are combined before combining the regionalimpairment rating with that from another region. Forexample, when there are multiple impairmentsinvolving abnormal motion, neurologic loss, andamputation of an extremity part, these impairmentsfirst should be combined for a regional extremityimpairment. The regional extremity impairment thenis combined with an impairment from anotherregion, such as from the respiratory system. Spinalimpairments in multiple regions are combined.Exceptions, as detailed in the musculoskeletal chap-ter, include impairments of the joints of the thumb,which are added, as are the ankle and subtalar jointsin the lower extremity: both situations include com-plex motions.

1.5 IncorporatingScience with ClinicalJudgment

The Guides uses objective and scientifically baseddata when available and references these sources.When objective data have not been identified, esti-mates of the degree of impairment are used, based onclinical experience and consensus. Subjective con-cerns, including fatigue, difficulty in concentrating,and pain, when not accompanied by demonstrableclinical signs or other independent, measurableabnormalities, are generally not given separateimpairment ratings. Chronic pain is discussed inChapter 18. Physicians recognize the local and dis-tant pain that commonly accompanies many disor-ders. Impairment ratings in the Guides already haveaccounted for commonly associated pain, includingthat which may be experienced in areas distant to thespecific site of pathology. For example, when a cer-vical spine disorder produces radiating pain downthe arm, the arm pain, which is commonly seen,has been accounted for in the cervical spine impair-ment rating.

The Guides does not deny the existence or impor-tance of these subjective complaints to the individualor their functional impact. The Guides recommendsthat the physician ascertain and document subjectiveconcerns. Because the presence and severity of sub-jective concerns varies among individuals with thesame condition, the Guides has not yet identified anaccepted method within the scientific literature toascertain how these concerns consistently affectorgan or body system functioning. The physician isencouraged to discuss these concerns and symptomsin the impairment evaluation.

Research is limited on the reproducibility and validity of the Guides.18-20 Anecdotal reports indicatethat adoption of the Guides results in a more stan-dardized impairment assessment process. As relevantresearch becomes available, subsequent editions ofthe Guides will incorporate these evidence-basedstudies to improve the Guides’ reliability and validity.


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Given the range, evolution, and discovery of newmedical conditions, the Guides cannot provide animpairment rating for all impairments. Also, sincesome medical syndromes are poorly understood andare manifested only by subjective symptoms, impair-ment ratings are not provided for those conditions.The Guides nonetheless provides a framework forevaluating new or complex conditions. Most adultconditions with measurable impairments can be eval-uated under the Guides. In situations where impair-ment ratings are not provided, the Guides suggeststhat physicians use clinical judgment, comparingmeasurable impairment resulting from the unlistedcondition to measurable impairment resulting fromsimilar conditions with similar impairment of func-tion in performing activities of daily living.

The physician’s judgment, based upon experience,training, skill, thoroughness in clinical evaluation,and ability to apply the Guides criteria as intended,will enable an appropriate and reproducible assess-ment to be made of clinical impairment. Clinicaljudgment, combining both the “art” and “science” ofmedicine, constitutes the essence of medical practice.

1.6 Causation,ApportionmentAnalysis, andAggravation

1.6a CausationPhysicians may be asked to provide an opinion aboutthe likelihood that a particular factor (injury, illness,or preexisiting condition) caused the permanentimpairment. Determining causation is importantfrom a legal perspective, as it is a factor in determin-ing liability.

The term causation has multiple meanings.Dorland’s Illustrated Medical Dictionary lists 12different types of “cause” including constitutional,exciting, immediate, local, precipitating, predispos-ing, primary, proximate, remote, secondary, specific,and ultimate.21 For purposes of the Guides, causationmeans an identifiable factor (eg, accident or expo-sure to hazards of a disease) that results in a med-ically identifiable condition.

Medical or scientifically based causation requires adetailed analysis of whether the factor could havecaused the condition, based upon scientific evidenceand, specifically, experienced judgment as towhether the alleged factor in the existing environ-ment did cause the permanent impairment.22

Determining medical causation requires a synthesisof medical judgment with scientific analysis.

The legal standard for causation in civil litigationand in workers’ compensation adjudication variesfrom jurisdiction to jurisdiction.23 The physicianneeds to be aware of the different interpretations ofcausation and state the context in which the physi-cian’s opinion is being offered.

1.6b Apportionment AnalysisApportionment analysis in workers’ compensationrepresents a distribution or allocation of causationamong multiple factors that caused or significantlycontributed to the injury or disease and resultingimpairment. The factor could be a preexisting injury,illness, or impairment. In some instances, the physi-cian may be asked to apportion or distribute a perma-nent impairment rating between the impact of thecurrent injury and the prior impairment rating. Beforedetermining apportionment, the physician needs toverify that all the following information is true for an individual:

1. There is documentation of a prior factor.

2. The current permanent impairment is greater as aresult of the prior factor (ie, prior impairment,prior injury, or illness).

3. There is evidence indicating the prior factorcaused or contributed to the impairment, based ona reasonable probability (> 50% likelihood).


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The apportionment analysis must consider the natureof the impairment and its possible relationship toeach alleged factor, and it must provide an explana-tion of the medical basis for all conclusions andopinions. Most states have their own customizedmethods for calculating apportionment. Generally,the most recent permanent impairment rating is cal-culated, and then the prior impairment rating is cal-culated and deducted. The remaining impairmentrating would be attributed or apportioned to the cur-rent injury or condition.

A common verbal formulation in the workers’ com-pensation context might state, “in cases of permanentdisability less than total, if the degree of disabilityresulting from an industrial injury or occupationaldisease is increased or prolonged because of a pre-existing physical impairment, the employer shall beliable only for the additional disability from theinjury or occupational disease.” 5

For example, in apportioning a spine impairment rating in an individual with a history of a spine con-dition, one should calculate the current spine impair-ment. Then calculate the impairment from anypreexisting spine problem. The preexisting impair-ment rating is then subtracted from the presentimpairment rating to account for the effects of theformer. This approach requires accurate and compa-rable data for both impairments.23

1.6c AggravationAggravation, for the purposes of the Guides, refersto a factor(s) (eg, physical, chemical, biological, ormedical condition) that alters the course or progres-sion of the medical impairment. For example, anindividual develops low back pain and sciatica asso-ciated with the finding of an L3-L4 herniated disk.Symptoms continue but are intermittent and do notinterfere with performing activities of daily living. Afew years later, the individual twists his body whilelifting a heavy package and develops constant,severe, acute low back pain and sciatica. Imagingstudies show no change in the herniated disk com-pared to earlier studies. The lifting is considered tohave aggravated a preexisting condition.

Terms such as causation, apportionment, and aggravation may all have unique legal definitions inthe context of the system in which they are used. Thephysician is advised to compare these definitionswith terminology accepted by the appropriate state orsystem.

1.7 Use of the GuidesBecause of the scope, depth, standardized approach,and foundation in science and medical consensus,the Guides is used worldwide to estimate adult per-manent impairment. A survey completed in 1999indicates that in the United States, 40 of 51 jurisdic-tions (50 states and the District of Columbia) use theGuides in workers’ compensation cases because ofstatute or regulations, or by administrative/legalpractice.24

The Guides is formally accepted through adoptivelanguage in each jurisdiction’s statutes (laws passedby a state legislature or the US Congress), court-made law (case law or precedent), or administrativeagency regulation (rules promulgated by administra-tive agencies such as a state workers’ compensationboard). It is this statutory, judicial, or regulatoryadoptive language that determines which edition ofthe Guides is mandated in a particular jurisdiction.Some states, such as Oregon and Florida, have devel-oped their own impairment criteria, modeled on theconcepts and material in the Guides. The Guides isalso extensively used by the federal systems, eg,FECA (Federal Employees’ Compensation Act). Themost recent edition of the Guides is recommended asthe latest blend of science and medical consensus.

Beyond the United States, the Guides is used inCanada, Australia, New Zealand, South Africa, andEuropean countries for different applications, includ-ing workers’ compensation, personal injury, and dis-ability claim management. There is a growinginternational trend to adopt a standardized, medicallyaccepted approach to impairment assessment such asin the Guides. As previously stated, the Guides is notto be used for direct financial awards nor as the solemeasure of disability. The Guides provides a stan-dard medical assessment for impairment determina-tion and may be used as a component in disabilityassessment.


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1.8 ImpairmentEvaluations inWorkers’Compensation

In the United States, workers’ compensation is a no-fault system for providing cash benefits, medicalcare, and rehabilitation services to individuals withwork-related injuries and diseases. All 50 states andthe District of Columbia have workers’ compensationacts. Most acts share similar features, although notwo are exactly alike. An employee normally mustexperience a “personal injury by accident arising outof and in the course of employment” to be eligiblefor benefits. All states provide benefits for workerswith occupational diseases, but that coverage isrestricted in many states. The claimant receives pay-ments to compensate for lost wages due to temporarytotal, temporary partial, permanent total, and perma-nent partial disability. Survivors receive death bene-fits. For each category of benefits, the stateprescribes a maximum and minimum weekly benefit.Many states stipulate partial compensation for a par-tial loss, based upon a proportion of the number ofweeks’ compensation allowed for total loss of thebody part.25 Determining eligibility of benefits andthe extent of disability is specified by statute andcase law.

Because schedules usually do not cover all condi-tions arising from injuries, many laws allow orrequire that, in unlisted cases of permanent disability,the jurisdiction must determine the percentage bywhich the “whole man” or “industrial use” of theemployee’s body was impaired. The board, commis-sion, or court also must consider the nature of theinjury and the employee’s occupation, experience,training, and age and then award proportional com-pensation. Medical information is essential for thedecision process in these cases.

Physicians who perform impairment and/or disabilityassessments for workers’ compensation purposesneed to identify the state workers’ compensation lawthat applies to the situation, which is usually the statewhere the incident occurred. The physician needs todetermine which edition of the Guides or other stateguidelines are required for these assessments. Thisinformation can usually be obtained from the stateworkers’ compensation board or the state medicalsociety. If the Guides is recommended or required,copies may be ordered through the AMA (see copy-right page) or other vendors.

Unfortunately, there is no validated formula thatassigns accurate weights to determine how a medicalcondition can be combined with other factors,including education, skill, and the like, to calculatethe effect of the medical impairment on futureemployment. Therefore, each commissioner or hear-ing official bases a decision on the assessment of theavailable medical and nonmedical information. TheGuides may help resolve such a situation, but it can-not provide complete and definitive answers. Eachadministrative or legal system that bases disabilityratings on permanent impairment defines its ownprocess of converting impairment ratings into a dis-ability rating that reflects the degree to which theimpairment limits the capacity to meet personal,social, occupational, and other demands, or to meetstatutory requirements. The Guides is a tool for eval-uation of permanent impairment.26, 27

Impairment percentages derived from the Guidescriteria should not be used as direct estimates ofdisability. Impairment percentages estimate theextent of the impairment on whole person func-tioning and account for basic activities of dailyliving, not including work. The complexity ofwork activities requires individual analyses.Impairment assessment is a necessary first stepfor determining disability.

1.9 EmployabilityDeterminations

Physicians with the appropriate skills, training, andknowledge may address some of the implications ofthe medical impairment toward work disability andfuture employment. The physician may be askedwhether an impaired individual can return to work ina particular job. The employer can provide a detailedjob analysis, with the actual and anticipated essentialrequirements of the job and a review of the workenvironment, including potential hazards and theneed for personal protective equipment. The physi-cian can then determine whether the individual’sabilities match the job demands. The physician needsto determine that the individual, in performing essen-tial job functions, will not either be endangered orendanger colleagues or the work environment. Forexample, it would be unsafe for an individual with anew, unstable seizure disorder to operate mechanicalequipment. The physician and other responsible per-sons should keep in mind the potential for impair-ment aggravation, as well as the possibility of


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changing an individual’s job responsibilities. After reviewing all the necessary information, thephysician may then make an objective and repro-ducible assessment of the ability of the individual tosafely perform the essential functions of the job.

More complicated are the cases in which the physi-cian is requested to make a broad judgment regard-ing an individual’s ability to return to any job in hisor her field. A decision of this scope usually requiresinput from medical and nonmedical experts, such asvocational specialists, and the evaluation of both sta-ble and changing factors, such as the person’s educa-tion, skills, and motivation, the state of the jobmarket, and local economic considerations.

Physicians who follow the procedures outlined in theGuides, who review the same information from med-ical and employment records, and who examine thesame patient with a stable condition should obtainapproximately the same findings.

1.10 Railroad andMaritime Workers

State workers’ compensation laws are not the onlymeans by which employees are compensated forinjuries or illnesses. In 1908, Congress passed theFederal Employer’ s Liability Act (FELA), which putin place a comprehensive injury compensation sys-tem for railroad workers. FELA provides a modifiedtort system for injured railroad workers, and it super-sedes state workers’ compensation laws. The JonesAct, passed in 1920, covers compensation for mar-itime workers injured due to a ship owner’s negli-gence. That law provides for the same rights andremedies that were extended through FELA.

A lawsuit filed under FELA must be based on therailroad’s negligence in providing the employee witha safe workplace. An injured employee must provethat the railroad should have foreseen that a condi-tion or activity might cause the injury or disease. Thetest determines whether the employer’s negligenceplayed any part in producing the injury. Recoverableamounts include those for necessary medicalexpenses, pain and suffering, loss of past earnings,and future losses due to diminished earning capacity.An important condition for recovery is that a physi-cian must diagnose the effects of the injury.

Under FELA, all cases must go before a jury orjudge, and there are no limits to the amount awarded.In contrast, the awards under state workers’ compen-sation systems are fixed and limited. Under FELA,the jury decides on the degree of the injured person’sdisability. The physician is obligated to obtain a reli-able history, confirm past employment by obtainingrecords, and collect all available medical information.

1.11 The Physician’sRole Based on theAmericans withDisabilities Act(ADA)

Physicians, particularly occupational physicians, arefrequently asked questions pertaining to work dis-ability and capacity, in light of increasing attention tocompliance with the Americans with DisabilitiesAct (ADA). The ADA is a civil rights law thatPresident Bush signed in 1990.28 It was intended “toprovide a clear and comprehensive national mandateto end discrimination against individuals with dis-abilities and bring those individuals into the eco-nomic and social mainstream of American life.”18

Under the ADA, individuals with disabilities are pro-tected against discrimination in such diverse areas asemployment, government service entitlement, andaccess to public accommodations (eg, health careservices, lodging).

The ADA defines disability as a physical or mentalimpairment that substantially limits one or more ofthe major life activities of an individual; a record ofimpairment; or being regarded as having an impair-ment (see Table 1-1). A person needs to meet onlyone of the three criteria in the definition to gain theADA’s protection against discrimination. The physi-cian’s input often is essential for determining the firsttwo criteria and valuable for determining the third.


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To be deemed “disabled” for purposes of ADA pro-tection, an individual generally must have a physicalor mental impairment that substantially limits one ormore major life activities. A “physical or mentalimpairment” could be any mental, psychological, orphysiological disorder or condition, cosmetic disfig-urement, or anatomical loss that affects one or moreof the following body systems: neurologic, specialsense organs, musculoskeletal, respiratory (includingspeech organs), reproductive, cardiovascular, hema-tologic and lymphatic, digestive, genitourinary, skin,and endocrine.29

Conditions that are temporary or not considered tobe severe (eg, normal pregnancy) are not consideredimpairments under the ADA. Other nonimpairmentsinclude features and conditions such as hair or eyecolor, left-handedness, old age, sexual orientation,exhibitionism, pedophilia, voyeurism, sexual addic-tion, kleptomania, pyromania, compulsive gambling,gender identity disorders not resulting from physicalimpairment, smoking, and current illegal drug use orresulting psychoactive disorders.

On June 23, 1999, in answer to a case seeking refine-ment of the definition of “who is disabled” under theADA, the Supreme Court stated that individuals whofunction normally with aids such as glasses or med-ication could not generally be considered disabled,despite their physical impairments.30

To have the protection of the ADA, a physical ormental impairment must substantially limit the abil-ity to perform a “major life activity.” Major lifeactivities include “basic activities that the averageperson in the general population can perform withlittle or no difficulty,” including caring for oneself,manual tasks, hearing, walking, learning, speaking,breathing, working, and reproduction. Major lifeactivities do not have to occur frequently or be partof daily life.31 Note that the major life activities listedhere include work, unlike the Guides’ impairmentcriteria.

The person must be presently, or perceived to be (notpotentially or hypothetically), substantially limited inorder to demonstrate a disability. It is difficult todetermine if an impairment “substantially limits” amajor life activity. An impairment’s nature, extent,duration, impact, and effect on the individual are allconsiderations in assessing the “substantiality” of thelimitations.32

For some major life activities, such as work, thephysician may provide an opinion on the medicalimpairment’s limitations. However, as indicated bythe recent Supreme Court ruling, how much a limita-tion of a major life activity results in a determinationof disability depends on the interaction between theremaining functional abilities and the possible typesof accommodation being sought.33

The third criterion that may establish protectionunder the ADA is an erroneous perception that theindividual is substantially limited in a major lifeactivity or is being discriminated against on the basisof a real or perceived characteristic that does not sub-stantially limit a major life activity.

It is the physician’s responsibility to determine if theimpairment results in functional limitations. Thephysician is responsible for informing the employerabout an individual’s abilities and limitations. It isthe employer’s responsibility to identify and deter-mine if reasonable accommodations are possible toenable the individual’s performance of essential jobactivities.

1.12 SummaryThe purpose of this chapter is to discuss the philo-sophical assumptions and appropriate use of theGuides. The physician needs to comply with pre-scribed local, state, and federal practices for impair-ment evaluations. Generally, the physician evaluatesall available information and provides as comprehen-sive a medical picture of the patient as possible,addressing the components listed in the Report ofMedical Evaluation form discussed in Chapter 2. A complete impairment evaluation provides valuableinformation beyond an impairment percentage, and itincludes a discussion about the person’s abilities andlimitations, including the ability to perform commonactivities as listed in Table 1-2. Combining the med-ical and nonmedical information, and includingdetailed information about essential work activities ifrequested, is a basis for improved understanding ofthe degree to which the impairment may affect theindividual’s work ability.


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References1. American Medical Association. Glossary. In: Guides to

the Evaluation of Permanent Impairment. Chicago, Ill:American Medical Association; 1971.

2. American Medical Association. Guides to the Evaluationof Permanent Impairment. 4th ed. Chicago, Ill: AmericanMedical Association; 1993.

3. Berkowitz M, Burton J. Permanent Disability Benefits inWorkers’ Compensation. Kalamazoo, Mich: UpjohnInstitute for Employment Research; 1987.

4. Cocchiarella L, Deitchman M, Nielsen N. Establishingdisability in various stages of HIV infection. Report of theCouncil on Scientific Affairs, American MedicalAssociation. Paper presented at: Interim Meeting of theAmerican Medical Association House of Delegates;December 1999; Chicago, Ill. Approved.

5. Idaho Code Section 406(1).

6. American Medical Association. Guides to the Evaluationof Permanent Impairment. 2nd ed. Chicago, Ill: AmericanMedical Association; 1984.

7. McDowell I, Newell C. Measuring Health: A Guide toRating Scales and Questionnaires. 2nd ed. New York, NY:Oxford University Press; 1996.

8. McWhinnie JR. Disability assessment in population sur-veys: results of the OECD common development effort.Rev Epidemiol Sante Publique. 1981;29:413-419.

9. Fries JF, Spitz PW, Young DY. The dimensions of healthoutcomes: the Health Assessment Questionnaire, disabil-ity and pain scales. J Rheumatol. 1982;9:789-793.

10. Hamilton BB, Granger CV, Sherwin FS, et al. A uniformnational data system for medical rehabilitation. In: FuhrerMJ, ed. Rehabilitation Outcomes: Analysis and Measurement. Baltimore, Md: Paul H. Brooks;1987:137-147.

11. Mahoney FI, Wood OH, Barthel DW. Rehabilitation ofchronically ill patients: the influence of complications onthe final goal. South Med J. 1958;51:605-609.

12. Katz S, Akpom CA. A measure of primary sociobiologicalfunctions. Int J Health Serv 1976;6:493-507.

13. Forer SK. Revised Functional Status Rating Instrument.Glendale, Calif: Rehabilitation Institute, GlendaleAdventist Medical Center; December 1981.

14. Fillenbaum GG. Multidimensional Functional Assessmentof Older Adults: The Duke Older Americans Resourcesand Services Procedures. Hillsdale, NJ: LawrenceErlbaum Associates; 1988.

15. Stewart AL, Kamberg CJ. Physical functioning measures.In: Stewart AL, Ware JE Jr, eds. Measuring Functioningand Well-being: The Medical Outcomes Study Approach.Durham, NC: Duke University Press; 1992:86-101.

16. Brandt EN Jr, Pope AM. Enabling America: Assessing theRole of Rehabilitation Science and Engineering.Washington, DC: National Academy Press; 1997.

17. World Health Organization. ICIDH: InternationalClassification of Impairments, Activities andParticipation: A Manual of Dimensions of Disablementand Health. (Beta-2 Draft). Available at:http://www.who.org/msa/mnh/ems/icidh/introduction.htm. Accessed October 7, 1999.

18. Gloss DS, Wardle MG. Reliability and validity ofAmerican Medical Association’s Guide to Ratings ofPermanent Impairment. JAMA.1982;248:2292-2296.

19. Rondinelli RD, Dunn W, Hassanein KM, et al. A simula-tion of hand impairments: effects on upper extremityfunction and implications towards medical impairmentrating and disability determination. Arch Phys MedRehabil. 1997;78:1358-1363.

20. McCarthy ML, et al. Correlation between the measures ofimpairment, according to the modified system of theAmerican Medical Association, and function. J Bone JointSurg Am. 1998;80(7):1034-1042.

21. Dorland’s Illustrated Medical Dictionary, 28th ed.Philadelpha, Pa: WB Saunders; 1994.

22. Rothman KJ, ed. Modern Epidemiology. 2nd ed.Philadelphia, Pa: Lippincott-Williams and Wilkins; 1998.

23. The Industrial Commission of Utah. Utah’s 1997Impairment Guides. Salt Lake City, Utah: The IndustrialCommission of Utah; 1997

24. Barth PS, Niss M. Permanent Partial Disability Benefits:Interstate Differences: Workers Compensation ResearchInstitute; 1999.

25. Bunn WB, Berté AP. The role of the physician in theworker’s compensation process. In: Hadler NM, BunnWB, eds. Occupational Problems in Medical Practice.New York, NY: Medical Publications, Inc; 1990:133-144.

26. Spieler EA, Barth PS, Burton JF Jr, Himmelstein J,Rudolph L. Recommendations to guide revision of theGuides to the Evaluation of Permanent Impairment.JAMA. 2000;283:519-523.

27. Cocchiarella L, Turk MA, Andersson G. Improving theevaluation of permanent impairment. JAMA. 2000;283:532-533.

28. Americans with Disabilities Act, HR Rep No. 101-485,pt 3, at 23 (1990), reprinted in 1990 USCCN 445, 446.

29. 29 CFR 1630.2(h)(1)(1997); HR Rep No. 101-485, pt 3,at 28 (1990), reprinted in 1990 USCCN 445, 450.

30. Sutton v United Airlines, 97 US 1943 (1999).

31. Interpretive Guidance on Title One, ADA, 29 CFR App1630.2.

32. 29 CFR 1630.2 (j) (2).

33. American Medical Association in Cooperation with theAmerican Academy of Physical Medicine andRehabilitation. The Americans with Disabilities Act: APractice of Accommodation. Chicago, Ill: AmericanMedical Association; 1998.


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2.1 Defining Impairment Evaluations

2.2 Who Performs Impairment Evaluations?

2.3 Examiners’ Roles and Responsibilities

2.4 When Are Impairment Ratings Performed?

2.5 Rules for Evaluation

2.6 Preparing Reports

IntroductionThis chapter describes how to use the Guides forconsistent and reliable acquisition, analysis, commu-nication, and utilization of medical informationthrough a single set of standards. Two physicians,following the methods of the Guides to evaluate thesame patient, should report similar results and reachsimilar conclusions. Moreover, if the clinical find-ings are fully described, any knowledgeable observermay check the findings with the Guides criteria. Thischapter provides information about the practicalapplication of the Guides and is to be used in con-junction with Chapter 1, which provides the concep-tual framework upon which the instructions in thischapter are based.

Practical Application of the Guides

Chapter 2

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2.1 DefiningImpairmentEvaluations

An impairment evaluation is a medical evaluationperformed by a physician, using a standard methodas outlined in the Guides to determine permanentimpairment associated with a medical condition. Animpairment evaluation may include a numericalimpairment percentage or rating, as defined in theGuides. An impairment evaluation is not the same asan independent medical evaluation (IME), whichis performed by an independent medical examinerwho evaluates but does not provide care for the indi-vidual. Impairment evaluations may be less compre-hensive than IMEs and may be performed by atreating physician or a nontreating physician,depending upon the state’s requirements and thepreferences of the individual, physician, and request-ing party. Examples of an impairment evaluation andcomponents of a comprehensive IME will be dis-cussed later in this chapter.

2.2 Who PerformsImpairmentEvaluations?

Impairment evaluations are performed by a licensedphysician. The physician may use information fromother sources, such as hearing results obtained fromaudiometry by a certified technician. However, thephysician is responsible for performing a medicalevaluation that addresses medical impairment in thebody or organ system and related systems. A statemay restrict the type of practitioner allowed to per-form an impairment evaluation, and some requireadditional state certification and other criteria, suchas a minimum number of hours of practice, beforethe physician is approved as an impairment evalua-tor. The physician is encouraged to check with thelocal workers’ compensation agency, industrial acci-dent board, or industrial commission concerningtheir prerequisites.

2.3 Examiners’ Rolesand Responsibilities

The physician’s role in performing an impairmentevaluation is to provide an independent, unbiasedassessment of the individual’s medical condition,including its effect on function, and identify abilitiesand limitations to performing activities of daily liv-ing as listed in Table 1-2. Performing an impairmentevaluation requires considerable medical expertiseand judgment. Full and complete reporting providesthe best opportunity for physicians to explain healthstatus and consequences to patients, other medicalprofessionals, and other interested parties such asclaims examiners and attorneys. Thorough documen-tation of medical findings and their impact will alsoensure that reporting is fair and consistent and thatindividuals have the information needed to pursueany benefits to which they are entitled.

The skills required for impairment evaluation areusually not taught during basic medical training,although some specialties such as occupational med-icine, physical medicine and rehabilitation, andorthopedics have emphasized elements of the evalua-tion such as occupational, functional, or anatomicalassessment.

In some cases, physicians may be asked to assess themedical impairment’s impact on the individual’sability to work. In the latter case, physicians need tounderstand the essential functions of the occupationand specific job, as well as how the medical condi-tion interacts with the occupational demands. Inmany cases, the physician may need to obtain addi-tional expertise to define functional abilities and lim-itations, as well as vocational demands.

As an impairment evaluator, the physician has theresponsibility to understand the regulations that per-tain to medical practice in his or her specific area, asin workers’ compensation or personal injury evalua-tions. It is also the responsibility of the physician toprovide the necessary medical assessment to theparty requesting the evaluation, with the examinee’sconsent. The physician needs to ensure that theexaminee understands that the evaluation’s purposeis medical assessment, not medical treatment.However, if new diagnoses are discovered, the physi-cian has a medical obligation to inform the request-ing party and individual about the condition andrecommend further medical assessment.


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2.4 When AreImpairment RatingsPerformed?

An impairment should not be considered permanentuntil the clinical findings indicate that the medicalcondition is static and well stabilized, often termedthe date of maximal medical improvement (MMI).It is understood that an individual’s condition isdynamic. Maximal medical improvement refers to adate from which further recovery or deterioration isnot anticipated, although over time there may besome expected change. Once an impairment hasreached MMI, a permanent impairment rating may beperformed. The Guides attempts to take into accountall relevant considerations in rating the severity andextent of permanent impairment and its effect on theindividual’s activities of daily living.

Impairments often involve more than one body sys-tem or organ system; the same condition may be dis-cussed in more than one chapter. Generally, the organsystem where the problems originate or where thedysfunction is greatest is the chapter to be used forevaluating the impairment. Thus, consult the visionchapter for visual problems due to optic nerve dys-function. Refer to the extremity chapters for neuro-logical and musculoskeletal extremity impairmentfrom an injury. However, if the impairment is due to astroke, the neurology chapter is most appropriate.Whenever the same impairment is discussed in differ-ent chapters, the Guides tries to use consistent impair-ment ratings across the different organ systems.

2.5 Rules for Evaluation

2.5a ConfidentialityPrior to performing an impairment evaluation, thephysician obtains the individual’s consent to sharethe medical information with other parties that willbe reviewing the evaluation. If the evaluating physi-cian is also that person’s treating physician, thephysician needs to indicate to the individual whichinformation from his or her medical record will be shared.

2.5b Combining Impairment RatingsTo determine whole person impairment, the physi-cian should begin with an estimate of the individual’smost significant (primary) impairment and evaluateother impairments in relation to it. It may be neces-sary for the physician to refer to the criteria and esti-mates in several chapters if the impairing conditioninvolves several organ systems. Related but separateconditions are rated separately and impairment rat-ings are combined unless criteria for the secondimpairment are included in the primary impairment.For example, an individual with an injury causingneurologic and muscular impairment to his upperextremity would be evaluated under the upperextremity criteria in Chapter 16. Any skin impairmentdue to significant scarring would be rated separatelyin the skin chapter and combined with the impairmentfrom the upper extremity chapter. Loss of nerve func-tion would be rated within either the musculoskeletalchapters or neurology chapter.

In the case of two significant yet unrelated condi-tions, each impairment rating is calculated sepa-rately, converted or expressed as a whole personimpairment, then combined using the CombinedValues Chart (p. 604). The general philosophy of theCombined Values Chart is discussed in Chapter 1.

2.5c ConsistencyConsistency tests are designed to ensure reproducibil-ity and greater accuracy. These measurements, suchas one that checks the individual’s lumbosacral spinerange of motion (Section 15.9) are good but imperfectindicators of people’s efforts. The physician must usethe entire range of clinical skill and judgment whenassessing whether or not the measurements or testsresults are plausible and consistent with the impair-ment being evaluated. If, in spite of an observation ortest result, the medical evidence appears insufficientto verify that an impairment of a certain magnitudeexists, the physician may modify the impairment rating accordingly and then describe and explain thereason for the modification in writing.

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2.5d Interpolating, Measuring, andRounding OffIn deciding where to place an individual’s impair-ment rating within a range, the physician needs toconsider all the criteria applicable to the condition,which includes performing activities of daily living,and estimate the degree to which the medical impair-ment interferes with these activities. In some cases,the physician may need additional information todetermine where to place an individual in the range.

As with any biological measurements, some variabil-ity and normal fluctuations are inherent in permanentimpairment ratings. Two measurements made by thesame examiner using the Guides that involve an indi-vidual or an individual’s functions would be consis-tent if they fall within 10% of each other.Measurements should also be consistent betweentwo trained observers or by one observer on two sep-arate occasions, assuming the individual’s conditionis stable. Repeating measurements may decreaseerror and result in a measurement that is closer toaverage function. The final calculated whole personimpairment rating, whether it is based on the evalua-tion of one organ system or several organ systems,should be rounded to the nearest whole number.

2.5e PainThe impairment ratings in the body organ systemchapters make allowance for any accompanyingpain. Chronic pain, also called chronic pain syn-drome, is discussed in the chapter on pain (Chapter 18).

2.5f Using Assistive Devices in EvaluationsIf an individual’s prosthesis or assistive device canbe removed or its use eliminated relatively easily, thephysician should usually test and evaluate the organsystem without the device. For example, ask thepatient to remove a hearing aid before testing audi-tory acuity. The examiner may choose also to test thesystem with the assistive device in place and thenreport both sets of results. The physician may alsochoose to report alterations in the individual’s organfunction with and without use of the device and chal-lenges that are posed by using the device, if any.

If the assistive device is not easily removable, aswith an implanted lens, evaluate the organ system’sfunctioning with the device in place. Test the visualsystem with the patient’s glasses or contact lenses inplace if they are used.

2.5g Adjustments for Effects of Treatmentor Lack of TreatmentIn certain instances, the treatment of an illness mayresult in apparently total remission of the person’ssigns and symptoms. Examples include the treatmentof hypothyroidism with levothyroxine and the treat-ment of type 1 diabetes mellitus with insulin. Yet it isdebatable whether, with treatment, the patient hasactually regained the previous status of normal goodhealth. In these instances, the physician may chooseto increase the impairment estimate by a small per-centage (eg, 1% to 3%).

In some instances, as with organ transplant recipientswho are treated with immunity-suppressing pharma-ceuticals or persons treated with anticoagulants, thepharmaceuticals themselves may lead to impair-ments. In such an instance, the physician should usethe appropriate parts of the Guides to evaluateimpairment related to pharmaceutical effects. Ifinformation in the Guides is lacking, the physicianmay combine an estimated impairment percent basedon the severity of the effect, with the primary organsystem impairment, by means of the CombinedValues Chart (p. 604).

A patient may decline surgical, pharmacologic, ortherapeutic treatment of an impairment. If a patientdeclines therapy for a permanent impairment, thatdecision neither decreases nor increases the esti-mated percentage of the individual’s impairment.However, the physician may wish to make a writtencomment in the medical evaluation report about thesuitability of the therapeutic approach and describethe basis of the individual’s refusal. The physicianmay also need to address whether the impairment isat maximal medical improvement without treatmentand the degree of anticipated improvement that couldbe expected with treatment.


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2.5h Changes in Impairment from PriorRatingsAlthough a previous evaluator may have considereda medical impairment to be permanent, unanticipatedchanges may occur: the condition may have becomeworse as a result of aggravation or clinical progres-sion, or it may have improved. The physician shouldassess the current state of the impairment accordingto the criteria in the Guides. If an individual receivedan impairment rating from an earlier edition andneeds to be reevaluated because of a change in themedical condition, the individual is evaluatedaccording to the latest information pertaining to thecondition in the current edition of the Guides.

Valid assessment of a change in the impairment esti-mate would depend on the reliability of the previousestimate and the evidence upon which it was based.If a prior impairment evaluation was not performed,but sufficient historical information is available tocurrently estimate the prior impairment, the assess-ment would be performed based on the most recentGuides criteria. However, if the information is insuf-ficient to accurately document the change, then thephysician needs to explain that decision and shouldnot estimate a change.

If apportionment is needed, the analysis must con-sider the nature of the impairment and its relation-ship to each alleged causative factor, providing anexplanation of the medical basis for all conclusionsand opinions. (Apportionment and causation are con-sidered more fully in Chapter 1 and are brieflydefined in the Glossary.) For example, in apportion-ing a spine impairment, first the current spineimpairment rating is calculated, and then an impair-ment rating from any preexisting spine problem iscalculated. The value for the preexisting impairmentrating can be subtracted from the present impairmentrating to account for the effects of the interveninginjury or disease. Using this approach to apportion-ment requires accurate information and data to deter-mine both impairment ratings. If different editions ofthe Guides are used, the physician needs to assesstheir similarity. If the basis of the ratings is similar, asubtraction is appropriate. If they differ markedly,the physician needs to evaluate the circumstancesand determine if conversion to the earlier or latestedition of the Guides for both ratings is possible. Thedetermination should follow any state guidelines andshould consider whichever edition best describes theindividual’s impairment.

2.6 Preparing ReportsA clear, accurate, and complete report is essential tosupport a rating of permanent impairment. The fol-lowing elements in bold type should be included inall impairment evaluation reports. Other elementslisted in italics are commonly found within an IMEor may be requested for inclusion in an impairmentevaluation.

2.6a Clinical Evaluation2.6a.1 Include a narrative history of the medicalcondition(s) with the onset and course of the condi-tion, symptoms, findings on previous examination(s),treatments, and responses to treatment, includingadverse effects. Include information that may be rele-vant to onset, such as an occupational exposure orinjury. Historical information should refer to any relevant investigations. Include a detailed list of prior evaluations in the clinical data section.

2.6a.2 Include a work history with a detailed,chronological description of work activities, specifictype and duration of work performed, materials usedin the workplace, any temporal associations with themedical condition and work, frequency, intensity,and duration of exposure and activity, and any pro-tective measures.

2.6a.3 Assess current clinical status, includingcurrent symptoms, review of symptoms, physicalexamination, and a list of contemplated treatment,rehabilitation, and any anticipated reevaluation.

2.6a.4 List diagnostic study results and outstand-ing pertinent diagnostic studies. These may include laboratory tests, electrocardiograms, exercise stressstudies, radiographic and other imaging studies,rehabilitation evaluations, mental status examina-tions, and other tests or diagnostic procedures.

2.6a.5 Discuss the medical basis for determiningwhether the person is at MMI. If not, estimate anddiscuss the expected date of full or partial recovery.


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2.6a.6 Discuss diagnoses, impairments.

2.6a.7 Discuss causation and apportionment, ifrequested, according to recommendations outlined in Chapters 1 and 2.

2.6a.8 Discuss impairment rating criteria,prognosis, residual function, and limitations.Include a discussion of the anticipated clinical courseand whether further medical treatment is anticipated.Describe the residual function and the impact of themedical impairment(s) on the ability to performactivities of daily living and, if requested, complexactivities such as work. List the types of affectedactivities (see Table 1-2). Identify any medical con-sequences for performing activities of daily living.

If requested, the physician may need to analyze differ-ent job tasks to determine if an individual has theresidual function to perform that complex activity.The physician should also identify any medical con-sequence of performing a complex activity such aswork.

2.6a.9 Explain any conclusion about the need forrestrictions or accommodations for standard activitiesof daily living or complex activities such as work.

2.6b Calculate the Impairment RatingCompare the medical findings with the impair-ment criteria listed within the Guides and calculatethe appropriate impairment rating. Discuss how spe-cific findings relate to and compare with the criteriadescribed in the applicable Guides chapter. Refer toand explain the absence of any pertinent data andhow the physician determined the impairment ratingwith limited data.

2.6c. Discuss How the Impairment RatingWas Calculated2.6c.1 Include an explanation of each impairmentvalue with reference to the applicable criteria of theGuides. Combine multiple impairments for a wholeperson impairment.

2.6c.2 Include a summary list of impairments andimpairment ratings by percentage, including calcula-tion of the whole person impairment.

On the following two pages is a standard form that theevaluator may use to ensure that all essential elementsare included in the impairment evaluation report. Theform may be reproduced without permission from theAmerican Medical Association. Most chapters includea summary form that identifies the salient, specific features to consider for each category of organ systemimpairment.


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Identifiers:

Patient name: ______________________________________________________________________________________________________________

Address:___________________________________________________________________________________________________________________

Claim #: ___________________________________________________________________________________________________________________

Date of birth: ______________________________________________________________________________________________________________

Date of injury or illness: ______________________________________________________________________________________________________

Sample Report for Permanent Medical Impairment

Examination date:_________________________________________________________________________________________________________________

Dates of care by examining physician: ______________________________________________________________________________________________

Examination location: _____________________________________________________________________________________________________________

Examining physician: ______________________________________________________________________________________________________________

Introduction: Purpose (impairment or IME evaluation, personal injury, workers’ compensation) and procedures (who performed the exam, patientconsent, location of examination)

__________________________________________________________________________________________________________________________________

__________________________________________________________________________________________________________________________________

__________________________________________________________________________________________________________________________________

Narrative history: Chief complaints, history of injury or illness, occupational history, past medical history, family history, social history, review of systems

__________________________________________________________________________________________________________________________________

__________________________________________________________________________________________________________________________________

__________________________________________________________________________________________________________________________________

Medical record review: Chronology of medical evaluation, diagnostic studies, and treatment for the injury or illness

__________________________________________________________________________________________________________________________________

__________________________________________________________________________________________________________________________________

__________________________________________________________________________________________________________________________________

Physical examination:

__________________________________________________________________________________________________________________________________

__________________________________________________________________________________________________________________________________

__________________________________________________________________________________________________________________________________


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Diagnostic studies:

__________________________________________________________________________________________________________________________________

__________________________________________________________________________________________________________________________________

__________________________________________________________________________________________________________________________________

Diagnoses and Impairments: (If requested, discuss work relatedness, causation, apportionment, restrictions , accommodations, assistive devices)

__________________________________________________________________________________________________________________________________

__________________________________________________________________________________________________________________________________

__________________________________________________________________________________________________________________________________

Work ability, work restrictions (If requested, review abilities and limitations in reference to essential job activities):

__________________________________________________________________________________________________________________________________

__________________________________________________________________________________________________________________________________

__________________________________________________________________________________________________________________________________

Impairment Rating Criteria: MMI residual function, limitations of activities of daily living, prognosis

__________________________________________________________________________________________________________________________________

__________________________________________________________________________________________________________________________________

__________________________________________________________________________________________________________________________________

Impairment Rating and Rationale Organ system and whole person impairment

Body part or system Chapter No. Table No. % Impairment of the Whole Person

a.

b.

c.

d.

Calculated total whole person impairment:_________%. Discussion of rationale of impairment rating and any possible inconsistencies

in the examination:

___________________________________________________________________________________________________________________________

___________________________________________________________________________________________________________________________

Recommendations: Further diagnostic or therapeutic follow-up care

__________________________________________________________________________________________________________________________________

__________________________________________________________________________________________________________________________________

__________________________________________________________________________________________________________________________________

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3.1 Principles of Assessment

3.2 Valvular Heart Disease

3.3 Coronary Heart Disease

3.4 Congenital Heart Disease

3.5 Cardiomyopathies

3.6 Pericardial Heart Disease

3.7 Arrhythmias

3.8 Cardiovascular Impairment Evaluation Summary

IntroductionThis chapter provides criteria for evaluating perma-nent impairments of the cardiovascular system andtheir effects on an individual’s ability to perform theactivities of daily living. The cardiovascular systemconsists of the heart, the aorta, the systemic arteries,and the pulmonary arteries. Impairment of the heartis the focus of this chapter; impairment of diseases ofthe aorta, the systemic arteries, and pulmonary arter-ies (including coronary and peripheral circulation)are included in Chapter 4.

The following sections have been revised from thefourth edition: (1) information about valvular heartdisease reflecting newly published guidelines fromthe American Heart Association and AmericanCollege of Cardiology; (2) information about coro-nary artery disease reflecting the important prognos-tic impact of left ventricular function on impairmentin individuals with coronary artery disease, and theinclusion of silent ischemia and coronary arteryspasm with regard to impairment; and (3) informa-tion about cardiomyopathy, including the impact ofHIV-related conditions that affect cardiac function.

The Cardiovascular System:Heart and Aorta

Chapter 3

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3.1 Principles ofAssessment

Before using the information in this chapter, theGuides user should become familiar with Chapters 1and 2 and the Glossary. C

guides.chap 01 [001-016]final guides 5th-min.pdf · chapter 1 1 1.1 history 1.2 impairment,...

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