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Summary: In comparison to body mass index (BMI), waist-hip ratio (WHR) demonstrated a stronger and more consistent correlation with all-cause mortality, and it remained unaffected by BMI.
Methodology: This study analyzed incident deaths data from the UK Biobank (2006-2022), incorporating information from 22 centers throughout the United Kingdom. The study encompassed 387,672 participants, divided into a discovery cohort (n = 337,078) and a validation cohort (n = 50,594), with the latter including 25,297 deaths and 2297 controls. The discovery cohort was utilized for establishing genetically determined adiposity metrics, while the validation cohort was employed for subsequent analyses. Associations between exposure and outcomes were examined through observational and mendelian randomization (MR) analyses.
Key Findings: Upon adjusted analysis, both measured BMI and fat mass index (FMI) exhibited a J-shaped association, whereas WHR displayed a linear association (hazard ratio of 1.41 per standard deviation increase). A significant association was observed between all three adiposity metrics and all-cause mortality, with odds ratios of 1.29 per standard deviation change in genetically determined BMI (P = 1.44×10−13), 1.45 per standard deviation change in genetically determined FMI (P = 6.27×10−30), and 1.51 per standard deviation change in genetically determined WHR (P = 2.11×10−9). WHR exhibited a stronger association with all-cause mortality when compared to BMI, although the difference was not statistically significant compared to FMI. The association of genetically determined BMI and FMI with all-cause mortality varied across quantiles of observed BMI, while WHR did not (P values of .04, .02, and .58 for BMI, FMI, and WHR, respectively).
Clinical Implications: The current recommendations from the World Health Organization for the optimal BMI range may not accurately apply to individuals with diverse body compositions, making them suboptimal for clinical guidance.
Source: This study was conducted by Irfan Khan, MSc, of the Population Health Research Institute, David Braley Cardiac, Vascular, and Stroke Research Institute, Hamilton, Ontario, Canada, along with colleagues. It was published online on September 20, 2023, in JAMA Network Open.
Limitations: The study population consisted of genetically homogeneous, White, and British individuals, potentially limiting the generalizability of the results to other racial or ethnic groups.
Disclosures: The study received funding from, and Khan received support from, the Ontario Graduate Scholarship–Masters Scholarship, awarded by the government of Ontario.
