Sex differences in the risk of frailty for mortality independent of disability and chronic diseases

Abstract

Objectives: To determine the effect of static and dynamic frailty on mortality in older men and women.

Design: A prospective cohort study with three 3-year measurement cycles.

Setting: Population based.

Participants: The sample was derived from the Longitudinal Aging Study Amsterdam and consisted of respondents who participated in two cycles (T1: 1992/1993 and T2: 1995/1996) and for whom there was complete data on disability and chronic diseases (N=2,257).

Measurements: Nine frailty markers were assessed at T1 and T2. The frailty markers were defined in two ways: low functioning at T2 (static frailty) and change in functioning between T1 and T2 (dynamic frailty). Survival time, calculated in days from T2 to January 1, 2000, was used as the outcome variable. Predictive ability was examined using Cox proportional hazards analyses separately for men and women.

Results: Women were frailer than men. Static frailty was significantly associated with mortality in men (relative risk (RR)=2.4) and in women (RR=2.6). Dynamic frailty was also associated with mortality in women (RR=2.6), but it was not significantly associated with mortality in men (RR=1.3). When disability and chronic diseases were included in the model as possible mediators, these RRs dropped to 1.6, 2.0, 2.1, and 1.2, respectively, of which the first three were still significant.

Conclusion: Frailty was associated with mortality to a greater extent in women than in men, and this effect was independent of disability and chronic disease. In men, the static definition of frailty was more predictive of mortality than the dynamic definition.