Disabling effects of chronic disease and impairment—II. Functional capacity limitations

Abstract

This study has examined the effect of functional capacity limitations on the severity of disability. Ideally, measures of disability take into account not only residual impairments and capacity limitations, but also residual capacities and adaptive capabilities of the individual. Personal, social and vocational factors affect individual capacity for adaptation to functional limitations. Attributes such as age, sex, education, and occupational experience, for example, are indicators of residual and adaptive capacity. Women, older people, the under-educated, and the unskilled appear to have less adaptive capacity or to face more demanding requirements; their ability to work was more affected by activity limitations. Young disabled people were more likely to adapt to work limitations than older people, regardless of extent of functional limitation; relatively slight functional limitations had more effect on the work capacity of women than of men; men appear to be more able than women to cope with impairment by accommodations on the job. The social consequence of disability were also directly related to activity and independence limitations. Work, household and social participation declined with increased functional limitations; reduced participation was closely reflected in increased severity of disability. The Functional Limitations Index also showed the selectivity of the public wage replacement and income support programs in relationship to disability criteria. Social security disability beneficiaries, for example, were concentrated among those with more severe activity limitations. The program was highly selective in terms of functional limitations and severity of disability. Entitlement to other income-maintenance programs tended to be less closely associated with functional limitations; program entitlement, however, was more closely related to functional limitation than to severity of disability. These findings clearly indicate that functional limitations are a primary consideration in the evaluation of disability. The index of functional limitations developed in this study showed a close relationship between the severity of disability and functional limitations. Data on activity limitations provide better prediction of the severity of disability than impairment indicators, such as chronic conditions or orthopedic aids. In combination with social indicators of capacity and adaptability, functional limitations indicators provide useful measures for the examination and prediction of disability and of behavioral changes in family and work activity.