Relative Fitness and Frailty of Elderly Men and Women in Developed Countries and Their Relationship with Mortality
Article first published online: 18 OCT 2005
Journal of the American Geriatrics Society
Volume 53, Issue 12, pages 2184–2189, December 2005
How to Cite
Mitnitski, A., Song, X., Skoog, I., Broe, G., Cox, J. L., Grunfeld, E. and Rockwood, K. (2005), Relative Fitness and Frailty of Elderly Men and Women in Developed Countries and Their Relationship with Mortality. Journal of the American Geriatrics Society, 53: 2184–2189. doi: 10.1111/j.1532-5415.2005.00506.x
- Issue published online: 18 OCT 2005
- Article first published online: 18 OCT 2005
- sex difference
Objectives: To investigate the relationship between accumulated health-related problems (deficits), which define a frailty index in older adults, and mortality in population-based and clinical/institutional-based samples.
Design: Cross-sectional and cohort studies.
Setting: Seven population-based and four clinical/institutional surveys in four developed countries.
Participants: Thirty-six thousand four hundred twenty-four people (58.5% women) aged 65 and older.
Measurements: A frailty index was constructed as a proportion of all potential deficits (symptoms, signs, laboratory abnormalities, disabilities) expressed in a given individual. Relative frailty is defined as a proportion of deficits greater than average for age. Measures of deficits differed across the countries but included common elements.
Results: In each country, community-dwelling elderly people accumulated deficits at about 3% per year. By contrast, people from clinical/institutional samples showed no relationship between frailty and age. Relative fitness/frailty in both sexes was highly correlated (correlation coefficient >0.95, P<.001) with mortality, although women, at any given age, were frailer and had lower mortality. On average, each unit increase in deficits increased by 4% the hazard rate for mortality (95% confidence interval=0.02–0.06).
Conclusion: Relative fitness and frailty can be defined in relation to deficit accumulation. In population studies from developed countries, deficit accumulation is robustly associated with mortality and with age. In samples (e.g., clinical/institutional) in which most people are frail, there is no relationship with age, suggesting that there are maximal values of deficit accumulation beyond which survival is unlikely.