Background: Frailty and body mass index (BMI) are known to be predictive of late life mortality, but little is known about the combined effects of frailty and BMI on mortality. Objective: This study investigated the influence of frailty status and BMI category on mortality in older adults. Methods: Data were from the Living Profiles of Older People Survey, a national survey of community-dwelling older people in Korea, with a baseline study of 11,844 Koreans aged 65 years and older in 2008 and a 3-year follow-up for mortality. Frailty was categorized as not frail, prefrail, and frail, based on five indicators (weight loss, exhaustion, physical activity, walking speed, and grip strength). BMI (kg/m²) was classified as underweight (<18.5), normal (18.5-24.9), overweight (25.0-29.9), or obese (≥30.0). A Cox proportional model was used to analyze the association of the combined frailty and BMI categories with all-cause mortality, adjusting for sociodemographics and health-related factors. Results: Adjusting for covariates, compared with the normal-weight nonfrail counterpart, the underweight or normal-weight prefrail/frail status demonstrated significantly increased rates of death. The obese frail respondents showed a significantly higher mortality risk (hazard ratio, 3.89; 95% confidence interval, 1.14-13.28). The overweight prefrail/frail group, however, exhibited no significant association with mortality. Conclusion: Among older people who were of normal weight or underweight, greater frailty was associated with poorer survival. Whereas being overweight tended to be neutral of the influence of frailty on mortality, the obese frail exhibited a significantly elevated rate of death.

Cognitive impairment was associated with a higher likelihood of frailty in community-dwelling older men and women. Total scores and specific subdomains of cognitive function were inversely associated with frailty.