The natural history of health-related quality of life: a 10-year cohort study.

BACKGROUND: Taking account of the impacts of institutionalization and death, this study describes the normative trajectories of health-related quality of life (HRQL) in Canada as individuals age from mid-to late life. METHODS: A nationally representative sample of 7,915 community-dwelling adults aged 40 and older in 1994/1995 was studied using 10 years of data from the longitudinal National Population Health Survey. Growth curve models of HRQL over age were fitted to describe the evolution of HRQL. Successive models were tested, first including only those living in a household throughout the entire period, then adding those who moved to an institution, and finally, including those who had died. RESULTS: HRQL remained generally stable until approximately age 70, when it began to decline. Excluding individuals when they were institutionalized, or ignoring the impact of death resulted in overly optimistic trajectories of HRQL in later years. INTERPRETATION: These results demonstrate the importance of following individuals into institutions and accounting for death in the production of realistic health estimates in aging populations.