Association of body roundness index with mortality in patients with diagnosed atherosclerotic cardiovascular disease: Analysis of NHANES 1999 to 2018

Body roundness index (BRI) is an innovative anthropometric indicator that reflects visceral adiposity and body composition. Although its association with mortality has been studied in both general and metabolic populations, its prognostic value in individuals with established atherosclerotic cardiovascular disease (ASCVD) remains unclear. This study aimed to investigate the association between BRI and all-cause and cardiovascular mortality in a nationally representative cohort of American adults diagnosed with ASCVD. Data were collected from 10 continuous cycles (1999-2018) of the National Health and Nutrition Examination Survey. In total, 2071 adults with self-reported ASCVD were included. The BRI was calculated from the waist circumference and height. Mortality outcomes were ascertained via linkage to the National Death Index in December 2019. Multivariate Cox proportional hazards regression models, restricted cubic splines, and subgroup analyses were used to assess associations. During a median follow-up of 6.9 years, 828 all-cause and 280 cardiovascular deaths occurred. A U-shaped nonlinear relationship was observed between the BRI and mortality (P-nonlinearity < .001). The inflection points were 5.54 for all-cause mortality and 6.09 for cardiovascular mortality. Below these points, the BRI was negatively correlated with mortality; above these points, each unit increase in the BRI significantly increased the risk of all-cause (hazard ratio = 1.114, 95% confidence interval: 1.113, 1.115) and cardiovascular mortality (hazard ratio = 1.101, 95% confidence interval: 1.099, 1.102). Subgroup analyses indicated that the associations were modified by gender, socioeconomic status, lifestyle behaviors, and comorbidities. In adults with ASCVD, the BRI is associated with both all-cause and cardiovascular mortality in a U-shaped manner, with the optimal risk observed within the range of approximately 5.5 to 6.0. BRI may serve as a valuable tool for risk stratification and personalized management in high-risk populations.