Advancing the taxonomy of disability in older adults

Refinement of the traditional task-based classification of disability is needed to advance the field of disability research and to inform clinical practice. We propose an enhancement of the taxonomy of disability that incorporates information about symptoms and impairments that directly contribute to disability. In the first step of this new development, we present evidence to support five categories of disability related to pain, balance, weakness, endurance, and other symptoms.

The Women's Health and Aging Study, begun in 1992, was a population-based study of older disabled women living in the Eastern region of Baltimore and surrounds. In-home examinations were conducted every 6 months for 3 years. During the second examination, the 879 participants were asked the main symptom cause of their disability for each activity with which they had difficulty. Symptom causes of disability in activities of daily living were grouped into five nonmutually exclusive categories as stated above. Descriptive analyses were used to compare groups according to sociodemographic, health, disease, and physical performance information.

Women with pain-related disability were younger, more obese, and had high prevalence of widespread pain and symptomatic osteoarthritis. Balance-related disability was related to having an age of 85 years or older, being Caucasian, and poor performance in tests of standing balance and gait. Women with weakness-related disability were older, more often African American and sedentary, had high prevalence of stroke and diabetes, and performed poorly in chair-stands and knee strength tests. Endurance-related disability was associated with low self-rated energy, depressive symptoms, smoking history, and lung and cardiovascular diseases.

The proposed refinement of the taxonomy of disability describes a set of empirically derived symptom and impairment-related disability groupings that have criterion and face validity. Further research about symptom and impairment-related disability in other populations of older persons is warranted.