Normative trajectories of health-related quality of life as individuals age: The importance of accounting for institutionalization and mortality

Background: As life expectancies in developed countries continue to increase, understanding patterns of health-related quality of life (HRQL) takes on greater importance. The purpose of this study was to describe normative aging trajectories of HRQL, taking into account the impact of institutionalization and mortality on the growth curves. Methods: A representative sample of 7,915 adults age 40 and older in 1994/95 was studied using data from the longitudinal Canadian National Population Health Survey. This survey follows individuals up every two years; ten years of data are available. Self-reported HRQL was assessed using the Health Utilities Index Mark 3 (HUI3). HUI3 scores are on a scale in which dead = 0.00 and perfect health = 1.00. Sex-specific growth curve models over age were assessed, including and excluding individuals when they were institutionalized, and accounting for mortality by using the HRQL score for dead. Results: HRQL remained generally stable until about age 70, when HRQL began to decline. The rate of HRQL decline varied depending on whether scores of those institutionalized were included, and how mortality was handled. Excluding individuals when they were institutionalized resulted in an overly optimistic description of HRQL in later years. Accounting for mortality resulted in less favorable HRQL trajectories than did ignoring the impact of mortality. Conclusions: Health related quality of life for both men and women in the Canadian population is high and stable until age 70. The results demonstrate the importance of following individuals in institutions and accounting for death in population health estimates.