Convergence of the Aging Rates for Healthy and Unhealthy Elderly at Advanced Ages

Aliaksandr Kulminski, Duke University
Svetlana V. Ukraintseva, Duke University
Kenneth C. Land, Duke University
Kenneth G. Manton, Duke University

We analyze the ability of a cumulative index of age-associated health disorders, called a “frailty index” (FI), to characterize individual rates of biological aging (BA) in elderly and, consequently, population heterogeneity in mortality models, using the National Long Term Care Survey data. We show that the FI age-patterns for “healthy” (low mean FI at younger ages) and “unhealthy” (high mean FI at younger ages) elderly converge at advanced ages suggesting that disorders might accumulate faster among the “healthy” than “unhealthy” individuals. Convergence of the FI age patterns in later ages is interpreted as a cross-sectional manifestation of compression of morbidity. Such behavior suggests existence of BA limits associated with given levels of health-maintenance in the society, i.e., they are not static and can be extended with improvements in health-care technologies. BA limits are found to be different for females and males corresponding to 109.4 and 92.5 years of chronological age, respectively.