Body mass index, functional disability and all-cause mortality in 330 000 older adults: The Shizuoka study

Aim A J-shaped association has been observed between body mass index (BMI) and all-cause mortality, but its relationship with functional disability is uncertain. We aim to clarify the association between BMI and functional disability, as well as all-cause mortality, by analyzing prefecture-wide annual health checkup data, and health and care insurance data. Methods The dataset analyzed in this study consisted of 332 405 community residents aged >= 65 years who subscribed to the National Health Insurance. Basic clinical information was obtained from the annual health checkup data. The presence of comorbidities at baseline and the incidence of functional disability and all-cause mortality were obtained from the health insurance data. Results The mean age and standard deviation of the study participants was 73.5 +/- 6.0 years. During a 4-year follow-up period, we observed 31 508 incident cases of functional disability and 16 640 deaths. The incidence rates of functional disability and all-cause mortality were higher in both lower and higher BMI subgroups, and the lowest risk was observed in the range of 21-27 kg/m(2) in men and 20-25 kg/m(2) in women. These associations were independent of age, sex, current smoking and possible confounding factors, including a cardiovascular diseases history, hospitalization during the half-year period before baseline, and baseline comorbidities. A similar association was observed between BMI and all-cause mortality even when individuals who developed functional disabilities before death were excluded from the analysis. Conclusions Maintaining the bodyweight within the recommended range could be an effective method of reducing the risk of functional disability and mortality. Geriatr Gerontol Int 2021; center dot center dot: center dot center dot-center dot center dot.