Abstract
OBJECTIVES: To describe the accumulation of aging-associated health disorders using a cumulative measure known as a frailty index (FI) and to evaluate its ability to differentiate long- and short-life phenotypes as well as the FI's connection to aging-associated processes in older people. DESIGN: Retrospective cross-sectional and longitudinal studies. SETTING: The National Long-Term Care Survey (NLTCS) data that assessed health and functioning of U.S. older individuals (> or =65) in 1982, 1984, 1989, 1994, and 1999 were analyzed. The NLTCS sample in each survey represents a mixture of longitudinal and cross-sectional components. PARTICIPANTS: Approximately 5,000 individuals in each survey. MEASUREMENTS: A cumulative index of health and well-being deficiencies (disabilities, signs, diseases) was calculated as a count of deficits observed in an individual divided by the total number of all considered deficits. RESULTS: Men and women who died before the age of 75 and those who died after the age of 85 exhibited remarkably similar FI frequency patterns despite the 10-year age difference between age profiles in these samples. Long life is consistently characterized in longitudinal analyses by lower FIs. FI dynamics are found to be strongly sex sensitive. CONCLUSION: The FI appears to be a sensitive age-independent indicator of sex-specific physiological decline in aging individuals and a sex-specific discriminator of survival chances. The FI is a promising characteristic suitable for improving sex-sensitive forecasts of risks of adverse health outcomes in older people.