Frailty and Mortality Outcomes in Cognitively Normal Older People: Sex Differences in a Population-Based Study

Objectives To characterize frailty in cognitively normal older adults at baseline and to investigate the relationship between frailty and mortality. Design Population-based prospective cohort study: Mayo Clinic Study of Aging. Setting Olmsted County, Minnesota. Participants Cognitively normal older persons aged 70 and older (mean age 78.8 ± 5.2, 50.2% male; N = 2,356). Measurements Frailty was assessed at baseline using a 36-item Frailty Index. Four frailty subgroups were identified based on the Frailty Index (≤0.10 (fit), 0.11-0.20 (at risk), 0.21-0.30 (frail), >0.30 (frailest)). All participants underwent comprehensive clinical and cognitive assessments. The association between frailty and mortality was assessed using Cox proportional hazards models. Results The median Frailty Index was 0.17 (interquartile range 0.11-0.22). Frailty increased with age and was more common in older men than in older women. Over a median follow-up of 6.5 years (range 7 days to 8.9 years), 500 of the 2,356 participants died, including 292 men. The frailest participants had the greatest risk of death (hazard ratio (HR) = 3.91, 95% confidence interval (CI) = 2.69-5.68). The association was stronger in women (HR = 5.26, 95% CI = 2.88-9.61) than men (HR = 3.15, 95% CI = 1.98-5.02). Conclusion Baseline frailty was common, especially in older men, and increased with age. Frailty was associated with significantly greater risk of death, particularly in women. These sex differences should be considered when designing a geriatric care plan.