Prediction of severe, persistent activity-of-daily-living disability in older adults

Abstract

In a prospective cohort of nondisabled adults aged 65 years or more in the Established Populations for Epidemiologic Studies of the Elderly (1981-1987 and 1985-1992), we used a competing risk approach to predict the 5-year risk of severe, persistent activities-of-daily-living (ADLs) disability, defined as dependence in ≥3 ADLs for 2 consecutive annual interviews or for 1 interview followed by death in the subsequent year. During 5 years, 6.8% developed severe, persistent ADL dependence, and 14.6% died without severe, persistent ADL dependence in the derivation cohort (n = 8,301); the corresponding percentages were 6.8% and 15.8% in the validation cohort (n = 4,177). A model based on age, current employment, visual impairment, self-rated health, diabetes mellitus, history of stroke or brain hemorrhage, cognitive function, and self-reported physical function showed good calibration. Discrimination, assessed by C statistics, for <70, 70-74, 75-79, and ≥80 years, was 0.75, 0.74, 0.65, and 0.66 in the derivation cohort and 0.70, 0.72, 0.70, and 0.65 in the validation cohort, respectively. In conclusion, a simple risk score based on routinely available clinical information can predict severe, persistent disability in 5 years. Future studies should examine whether physical performance measures can further improve prediction in the oldest old.

Keywords: activities of daily living; aged; prognosis.

Figure 1.

Calibration plot of a cause-specific hazards model and a standard Cox regression model for the prediction of severe, persistent activity-of-daily-living dependence in the validation cohort, the Established Populations for Epidemiologic Studies of the Elderly, United States, 1981–1987 and 1985–1992. The risk was estimated as the 5-year cumulative incidence of severe, persistent activity-of-daily-living dependence from the cause-specific hazards model that accounted for competing risk.

Figure 2.

Score sheet to estimate 5-year risk of severe, persistent activity-of-daily-living dependence, the Established Populations for Epidemiologic Studies of the Elderly, United States, 1981–1987 and 1985–1992. The risk was estimated as the 5-year cumulative incidence of severe, persistent activity-of-daily-living dependence from the cause-specific hazards model that accounted for competing risk. Cognitive function was considered “normal” if the number of errors on the Short Portable Mental Status Questionnaire was ≤2; “mildly impaired” if 3 or 4; and “moderately to severely impaired” if ≥5 (22).