Perceived causes of disability added prognostic value beyond medical conditions and functional status

This study's objective was to determine the incremental benefit of respondent subjective attribution of functional decline beyond relying solely on disease burden in predicting survival.

A total of 9447 older adults from the Second Longitudinal Study on Aging, a probability sample of community dwelling adults aged 70 or older, were evaluated. Survival was based on status at follow-up interview 3-4 years after baseline interview. Logistic regression was performed using demographic variables and coexisting diseases as a baseline, then adding functional status measures (ADL, IADL) and individual subjective attribution of functional limitation in subsequent models.

The predictions improved significantly with the addition of functional status measures (P<0.001) and the individual subjective attribution of functional limitation (P<0.001). For example, the probability of mortality for individuals with cancer was 17.3%, but 28.8% of those with cancer and functional limitations died as did 50% of those with cancer who reported functional limitations attributable to cancer.

Among persons who can make a specific attribution of their functional limitation, the attribution may have value as a marker of severity of disease and serve as a good predictive measure for mortality, especially in specific illnesses such as cancer.