Successful aging: measuring the years lived with functional loss.

Current research of risk factors potentially associated with successful aging faces the difficulty of taking into consideration two distinct outcome measures: survival and functioning. Previous studies either used successful aging measures restricted to survivors or presented more than one outcome measure to handle the dual outcome. This article illustrates the utility of health expectancy measures, based on life tables, to integrate the effects of survival and functioning across all ages. It is shown that three hypothetical successful aging strategies, considered equally successful according to the traditional measures restricted to survivors, are associated with vastly different changes in the years lived with and without disability. Furthermore, the intervention considered most successful when considering multiple successful aging measures, was associated with the largest increase in the time lived with disability. It is recommended that research on successful aging should be based on summary measures of population health that reflect both survival and functioning throughout life. These will provide more relevant information than is currently available for individuals and societies to evaluate and choose between successful aging strategies.