Cumulative Index of Age-Associated Health Disorders as a Major Indicator of Aging Processes and Mortality Risks in Elderly Populations: Results from Analyses of the National Long-Term Care Survey
Aliaksandr Kulminski, Duke University
Igor Akushevich, Duke University
Kenneth C. Land, Duke University
Konstantin G. Arbeev, Duke University
We analyze the ability of a cumulative index of age-associated health and quality-of-life disorders, called a “frailty index” (FI), to characterize individual rates of biological aging in the elderly and, consequently, population heterogeneity in mortality models, using National Long Term Care Survey (NLTCS) data. We show that the FI in the NLTCS exhibits an accelerated increase with age resembling mortality-curve behavior. Such patterns suggest that FI may be a better indicator of aging than chronological age. Deficits accumulate faster in non-disabled elderly who, at younger ages, had a lower mean FI than in disabled individuals, who showed a higher FI at younger ages. We interpret this as a cross-sectional manifestation of compression of morbidity. Age-patterns for disabled and non-disabled males and females tend to converge at advanced ages. This suggests the existence of biological age limits associated with given levels of health-maintenance in the society.