Healthy Life Expectancy for Individuals

Healthy life expectancy is traditionally measured as a population statistic that assigns the same expected healthy remaining lifetime to all individuals of the same age. We develop healthy life expectancy as an individual concept by combining projected health trajectories with survival probabilities conditional on an individual's observed frailty. Using longitudinal data from the Health and Retirement Study, we show that the logarithm of the frailty index increases approximately linearly with age after controlling for permanent individual heterogeneity, implying an exponential law of deficit accumulation. Together with a sex-specific Gompertz mortality model, this regularity provides a simple framework for computing individual healthy life expectancy. The resulting measure reveals substantial heterogeneity in healthy remaining lifetime among individuals of the same age. Although sex, education, geography, and race and ethnicity are associated with systematic differences, most variation occurs within rather than between these groups.