Associations of body roundness index with cardiovascular disease and mortality among patients with metabolic syndrome

Abstract Aims The prevalence of metabolic syndrome (MetS) is increasing due to ageing populations and lifestyle changes, making it crucial to understand the relationship between body fat distribution and cardiovascular outcomes. Traditional measures such as body mass index (BMI) have limitations in assessing abdominal obesity. The body roundness index (BRI), a novel anthropometric measure combining waist circumference and height, has shown promise in evaluating this risk. This study aims to explore the association between BRI and cardiovascular disease (CVD) prevalence and mortality in a nationally representative sample of US adults with MetS. Materials and Methods This retrospective study used data from the National Health and Nutrition Examination Surveys (NHANES) 2001–2016, including 10 527 MetS‐diagnosed participants. BRI was calculated and the cohort was divided into quartiles. Logistic regression and Cox proportional hazards models assessed the relationship between BRI and CVD prevalence, all‐cause mortality and cardiovascular‐specific mortality. Kaplan–Meier curves and restricted cubic spline analyses visualized survival patterns and non‐linear relationships, with sensitivity analysis for validation. Results Higher BRI quartiles were significantly associated with increased CVD prevalence (odds ratio [OR]: 1.56 [1.32–1.84], p < 0.001). In the fully adjusted model, BRI demonstrated a U‐shaped relationship with all‐cause and cardiovascular mortality, with a threshold value of 6.89 ( p for non‐linear ≤0.001). Above this threshold, each additional unit in BRI was linked to a 9% increase in cardiovascular mortality risk (hazard ratio [HR]: 1.09 [1.02–1.15], p = 0.006) and an 8% rise in overall mortality (HR: 1.08 [1.04–1.12], p < 0.001). Conversely, BMI showed a paradoxical relationship with reduced mortality risk in unadjusted models, which became insignificant after adjusting for confounders ( p = 0.195; 0.144). Conclusions BRI might be a more reliable predictor of cardiovascular outcomes and mortality in MetS patients than BMI. The identified threshold value of BRI can assist clinicians in making accurate prognostic evaluations. However, findings may vary by age and gender, underscoring the need for further research in diverse populations.