Dose-response relationship between body mass index and risks of all-cause mortality and disability among the elderly: A systematic review and meta-analysis

Abstract

Background & aims: To establish the relationship between body mass index (BMI) and risks of mortality and disability among the Elderly.

Methods: A systematic review and dose-response meta-analysis was performed. PubMed, Embase, Cochrane library, and Google Scholar were searched systematically until December 2017 for relative studies reporting the hazard ratio (HR) and corresponding 95% confidence intervals (CIs) of all-cause mortality or disability across different BMI categories.

Results: 44 studies (37 studies on all-cause mortality and 9 studies on disability) were included in the meta-analysis. The restricted cubic spline model presents a U-shape trend, which suggests a relationship between BMI and all-cause mortality. As BMI increased, the all-cause mortality decreased from 1.49 (95% CI: 1.31, 1.71) to 0.96 (95% CI: 0.93, 0.98) in the 14.0-27.9 range and increased from 0.96 (95% CI: 0.94, 0.99) to 1.95 (95% CI: 1.37, 2.77) in the 28.0-47.9 range. In comparison with the reference BMI (23.0-23.9), the 24.0-29.0 BMI presented a significant protective effect, whereas <23.0 BMI and >33.0 BMI presented a significant risk effect on all-cause mortality. For disability, the restricted cubic spline model shows a nonlinear relationship. Individuals with >28.0 BMI and 33.0 BMI were 19% (95% CI: 1.01, 1.40) and 43% (95% CI: 1.13, 1.82) more prone to disability risks compared with those in the reference group, respectively.

Conclusions: The lower-end recommended BMI range, underweight, and obesity among the elderly is associated with significantly increased risks of mortality and disability. The 23.0-28.0 BMI range may be the healthy weight range for the elderly group.

Keywords: Body mass index; Disability; Meta-analysis; Mortality; Obesity.