Predictors of five-year mortality in older Canadians: The Canadian study of health and aging

OBJECTIVE: Based on the Canadian Study of Health and Aging (CSHA), to determine the importance of cognitive status, sociodemographic factors, functional status, and other health related factors as predictors of 5-year overall mortality in older Canadians. DESIGN, SETTING AND PARTICIPANTS: Two partially overlapping groups from the Canadian Study of Health and Aging (1991) were identified: (1) older people living in the community (n = 8949) who had a screening interview (larger sample, fewer variables) and (2) older people who underwent an extensive clinical examination (smaller sample, more objective variables; n = 2914). Deaths in the subsequent 5 years were determined from death certificates and interviews with the caregivers. Multivariate logistic regression models, with death within 5 years as the outcome, were developed separately for men and women. Predictor variables were introduced in the following groups: sociodemographic factors, physical and cognitive status, and physical illnesses and life style factors. Parallel models were developed for the screening sample and for the clinical sample. RESULTS AND DISCUSSION Five-year mortality ranged from 10.0% (women aged 65-74 living in the community) to 88.1% (men aged 85 and older living in institutions). Multivariate models showed that the odds of death within 5 years increased with age. This effect remained after adjustment for all other variables. Odds of death increased with institutionalization and with increasing cognitive and physical impairment. Although vision and hearing problems and the presence of heart disease, stroke, and diabetes were all strongly related to 5-year mortality in univariate, unadjusted analyses, their contributions were minimal in the multivariate analyses. Increased Body Mass Index was associated with lower mortality in both univariate and multivariate analyses. CONCLUSIONS: This population-based study supported the importance of gender, age, functional status, cognition, and health status in predicting 5-year mortality,and after accounting for cognitive status, physical status, and specific disease variables, the difference in mortality between older people in the community and in institutions was reduced. Knowledge about survival and prognosis is important not only for the planning of long-term facilities and home care, but it can also be helpful for clinical decision-making and for family and caregivers.