Relationship of Higher-level Functional Capacity With Long-term Mortality in Japanese Older People: NIPPON DATA90

BACKGROUND: Basic and instrumental activities of daily living (BADL and IADL, respectively) are known predictors of mortality. However, the relationship between higher-level functional capacity (HLFC) and mortality and related sex differences have rarely been investigated. METHODS: A prospective population-based cohort study was conducted in 1,824 older residents (≥65 years) with independent BADL from 300 randomly selected areas in Japan from 1995, and the participants were followed up until 2010. Using the Cox proportional hazards model, the relationship between HLFC and mortality risk was investigated, with adjustment for possible confounders. HLFC was assessed using the Tokyo Metropolitan Institute of Gerontology Index of Competence. Baseline data were collected using a questionnaire or by home-visit interviews. RESULTS: During an average 12.2-year follow-up, all-cause death was observed in 836 (45.8%) participants. Impaired HLFC was significantly associated with mortality (hazard ratio [HR] 1.37; 95% confidence interval [CI], 1.13–1.65). Lower social role was significantly associated with higher mortality risk in men (HR 1.38; 95% CI, 1.13–1.68). Lower IADL and intellectual activity were significantly associated with higher mortality risk in women (HR 1.50; 95% CI, 1.15–1.95 and HR 1.46; 95% CI, 1.19–1.79, respectively). The relationship between HLFC and mortality risk showed a similar tendency among cardiovascular diseases, stroke, cancer, and pneumonia. CONCLUSION: Impaired HLFC was associated with a high risk of all-cause mortality among community-dwelling older people with independent BADL. In particular, social role in men and IADL and intellectual activity in women were associated with long-term mortality risk.