Body Roundness Index Versus Body Mass Index for Predicting Cardiovascular Mortality: Insights from a National Cohort

Abstract

Background and purpose: Body mass index (BMI) is widely used to estimate adiposity but does not reflect fat distribution and may underestimate cardiovascular risk. The body roundness index (BRI), incorporating waist circumference and height, better reflects visceral adiposity. This study compared BRI and BMI as predictors of cardiovascular and heart-failure mortality in a nationally representative U.S. cohort.

Methods: Data from 31,351 adults ≥20 years in NHANES 1999–2018 were analyzed, excluding individuals with prior cardiovascular disease or cancer. BRI was calculated using a validated formula and divided into quintiles; BMI used World Health Organization categories. Cardiovascular and heart-failure mortality were identified through National Death Index linkage. Weighted Cox proportional-hazards models estimated associations between BRI or BMI and mortality, adjusting for demographic, socioeconomic, lifestyle, and clinical factors including hypertension, diabetes, and lipid-lowering therapy. Restricted cubic splines assessed non-linearity, and Harrell’s C-index evaluated discrimination.

Results: Over a median follow-up of 10 years, 883 cardiovascular deaths occurred, including 243 from heart failure. Compared with the middle BRI quintile, the highest quintile was associated with a 54% higher cardiovascular mortality risk (adjusted HR 1.54; 95% CI 1.13–2.08). In contrast, BMI ≥30 kg/m² showed only a borderline increase (HR ≈ 1.18; 95% CI 0.98–1.42). BRI demonstrated a modest U-shaped association, whereas BMI showed a weaker linear trend. Replacing BMI with BRI improved discrimination (C-index 0.77 vs 0.74). Patterns were similar for heart-failure mortality, where high BRI predicted a 1.6-fold risk increase, while BMI categories were not independently associated after adjustment.

Conclusions: BRI was a stronger predictor of cardiovascular and heart-failure mortality than BMI, likely due to better representation of visceral fat. Incorporating BRI into clinical risk assessment may improve identification of high-risk individuals, particularly those with central obesity who may be missed by BMI. Future studies should validate BRI thresholds and assess integration with biomarker-based HF risk models.