Disability? Impairment?

Physicians and lawyers mean different things when they use the terms Disability and Impairment. The principal determinants of (legal) impairment are clinically unmeasurable. Assessment of functional limitation may be objective, but opinion about impairment and disability inevitably depends on physician attitudes and prejudices.

PRACTICE POINT

Either use medical terminology when communicating with physicians about disablement or provide legal definitions

Physicians and lawyers mean different things when they use the terms Disability and Impairment. Medical definitions of Disability, Impairment and Handicap are internally consistent, as are legal definitions, but the two systems of thought are incompatible. Just as most physicians do not understand legal causation, medicine and the law use the same disablement terminology quite differently.

When a physician says disability he means (legal) impairment; medical impairment is closer to (legal) handicap.

Medical definitions (World Health Organisation):

Impairment: the loss of a psychologic, physiologic, or anatomic structure or function.

Disability: the loss of ability to perform tasks in a normal manner.

Handicap: the limitations on the person's ability to fulfill normal social roles and obligations.

The principal determinants of (legal) impairment are clinically unmeasurable. First, then, there is a semantic problem that must be resolved by translation from legalese to medicalese.

PRACTICE POINT

(Legal) impairment in, and disability awards for, many musculoskeletal conditions are determined more by subjective pain and psychological distress than by objective functional limitation

More problematic is the conceptual problem. The law, with its precise definitions, asks the physician to provide an objective assessment of (legal) impairment. The starting point is diminished function, measurement of which can be replicated, with fairly close agreement between different medical examiners.

However, as the examining physician knows, the principal determinants of (legal) impairment are not objective functional limitation, but pain, psychological distress, fatigue, and sleep deprivation, none of which can be clinically measured in a meaningful way1.

Unfortunately and contrary to popular belief, there is a poor correlation between the nature or extent of an injury and the resulting pain and suffering1a While reduced joint movement and muscle bulk can be quantified, and percentages of disability allotted by reference to standard tables, there is a danger of sacrificing what is important for what is measurable.

PRACTICE POINT

Main factors in determining musculoskeletal (legal) Impairment:
1. pain
2. psychological distress
3. fatigue
4. sleep deprivation

Indeed, disability awards have been shown to be determined less by dysfunction and more by pain in some musculoskeletal conditions2, and by psychological distress additionally in others3.

Assessment of functional limitation may be objective, but opinion about impairment and disability inevitably depends on physician attitudes and prejudices. Both the treating physician and the claimant independent medical assessor have vested interest in maximising (legal) impairment for medicolegal purposes, whereas the defence physician is there to minimise. Thus, the individual physicians' differences in credulity of, and empathy for, the claimant, rather than any objective determination, cause the sometimes wide discrepancy in medical expert opinion.

Legal process inevitably falls far short of its goal of dispassionate determination.

PRACTICE POINT

It may be worth crossexamining the highly subjective development of impairment assessment

Copyright 2008 Electronic Handbook of Legal Medicine