Impairment, disability, and the ICIDH model. III: Underlying disease, impairment, and disability.

Secondary analysis of data carried out in a national survey of the disabled is used to explore the relationship between underlying condition, impairment and disability, where the conditions are considered in three groups depending on whether they affect control, mechanical performance or energy. Comparison of impairment and disability profiles highlights the role of functional limitation in mediating between disease and disability. Disability profiles were found to be less associated with the underlying condition than were impairment profiles, but this can to some extent be explained by the nature of the functional limitation.