Physical frailty and survival time after the onset of functional disability: Is there a sex difference?

Background: Physical frailty accelerates the timing of both subsequent disability and death; however, evidence regarding the impact of frailty on the period from disability onset to death and sex differences of this impact is lacking. The aim of this study was to examine the relationship among physical frailty, disability, death, and sex differences.

Methods: This Japanese cohort study included 10,524 community-dwelling people aged ≥65 years. Physical frailty was operationalized by key phenotypes as per Fried's criteria (slowness, weakness, exhaustion, weight loss, and low activity) at baseline. We calculated hazard ratios (HRs) with 95% confidence intervals (CIs) for disability onset and post-disability survival according to the frailty status.

Results: During a 5-year follow-up, the risk of disability onset for pre-frailty (HR: 1.74, 95% CI: 1.51-2.00) and frailty (HR: 3.27, 95% CI: 2.77-3.87) were significantly higher than that for robust people. Furthermore, among participants who developed disabilities within 5 years (n = 1481), the risk of post-disability death for pre-frailty was not different from that for robust (HR: 1.49, 95% CI: 0.99-2.24), but frailty showed a higher risk of post-disability death than did robust people. (HR: 1.75, 95% CI: 1.13-2.72). In the sex-stratified analysis, although the female group showed no association between frailty status and post-disability death (HR: 1.21, 95% CI: 0.63-2.33 in pre-frailty; HR: 1.24, 95% CI: 0.60-2.57 in frailty), the male group showed higher risk of post-disability death in both pre-frailty (HR: 1.74, 95% CI: 1.03-2.96) and frailty (HR: 2.32, 95% CI: 1.32-4.09).

Conclusions: Physical frailty shortens the period from disability onset to death. Additionally, the impact of frailty on post-disability death is greater for males than for females. Our findings suggest that physical frailty is an important clinical indicator distinct from disability and that interventions to prevent and address frailty in men need further investigation.