American Journal of Epidemiology Advance Access published online on September 28, 2007
American Journal of Epidemiology, doi:10.1093/aje/kwm270
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Original Contribution |
Life-Space Constriction, Development of Frailty, and the Competing Risk of Mortality
The Women's Health and Aging Study I
1 Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD
2 Center on Aging and Health, Johns Hopkins Medical Institutions, Baltimore, MD
3 Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD
Correspondence to Dr. Qian-Li Xue, Johns Hopkins School of Medicine, 2024 E. Monument Street, Suite 2-700, Baltimore, MD 21205 (e-mail: qxue{at}jhsph.edu).
Received for publication March 20, 2007. Accepted for publication August 22, 2007.
Frailty is a common clinical syndrome in older adults that carries an increased risk for poor health outcomes. Little is known about the behavioral antecedents of frailty. In this study, the authors hypothesized that constriction of life space identifies older adults at risk for frailty, potentially a marker of already-decreased physiologic reserve. The authors analyzed the 3-year (1992–1995) cumulative incidence of frailty using a previously validated clinical phenotype in relation to baseline life-space constriction among 599 community-dwelling women aged 65 years or older who were not frail at baseline. Frailty-free mortality (i.e., death prior to observation of frailty) was treated as a competing risk. Multivariate survival models showed that, compared with women who left the neighborhood four or more times per week, those who left the neighborhood less frequently were 1.7 times (95% confidence interval: 1.1, 2.4; p < 0.05) more likely to become frail, and those who never left their homes experienced a threefold increase in frailty-free mortality (95% confidence interval: 1.4, 7.7; p < 0.01), after adjustment for chronic disease, physical disability, and psychosocial factors. Together, these data suggest that a slightly constricted life space may be a marker and/or risk factor for the development of frailty that may prove useful as a screening tool or a target of intervention.
adaptation, physiological; aged; frail elderly; homebound persons
Abbreviations: ADL, activities of daily living; IADL, instrumental activities of daily living; MMSE, Mini-Mental State Examination; WHAS I, Women's Health and Aging Study I