U-shaped association of body roundness index with all-cause and cardiovascular mortality in individuals with chronic kidney disease

Purpose This study aimed to investigate the association between body roundness index (BRI) and deaths from all causes and cardiovascular disease (CVD) in participants with chronic kidney disease (CKD).Materials and methods The data was sourced from the National Health and Nutrition Examination Survey (NHANES) 1999–2018. Cox proportional hazards regression along with restricted cubic splines were applied to assess the associations of BRI with deaths from all causes and CVD in individuals with CKD.Results In total, 8,000 individuals were included in the final analysis. In participants with CKD, there was a nonlinear U-shaped association between BRI and deaths from all causes and CVD, with inflection points at 6.29 and 6.04. When BRI was below the inflection points, each unit increment of BRI correlated with a 11% reduction in deaths from all causes [HR: 0.89 (0.84–0.94), p < 0.001] and a 15% reduction in deaths from CVD [HR: 0.85 (0.75–0.95), p = 0.006)]. Conversely, when BRI surpassed the inflection points, each unit increment of BRI was linked to a 9% rise in deaths from all causes [HR: 1.09 (1.03–1.14), p = 0.001] and a 10% rise in deaths from CVD [HR: 1.10 (1.02–1.20), p = 0.019].Conclusion In this nationally representative study, we found a nonlinear U-shaped association between BRI and deaths from all causes and CVD among participants with CKD, with inflection points at 6.29 and 6.04. Further research is required to establish the optimal range of BRI as a measure of visceral fat deposition.