Association between body roundness index and new-onset stroke in patients with cardiovascular-kidney-metabolic syndrome stages 0–3: insights from CHARLS

Stroke is a leading cause of mortality and disability among middle-aged and elderly populations in China. Patients with Cardiovascular-Kidney-Metabolic (CKM) syndrome stages 0–3 have a significantly increased risk of stroke due to multisystem synergistic damage, yet convenient indicators for stroke risk assessment in this population remain limited. As a novel anthropometric index, Body Roundness Index (BRI) more accurately reflects visceral fat distribution compared to Body Mass Index (BMI) and waist circumference (WC), but its association with stroke risk in this specific population remains unclear. Based on the China Health and Retirement Longitudinal Study (CHARLS) cohort, 7,401 participants with CKM syndrome stages 0–3 were enrolled, with 2011 as the baseline and follow-up conducted until 2020. Multivariate Cox proportional hazards regression models were used to analyze the association between BRI and new-onset stroke. Restricted Cubic Spline (RCS) regression was applied to explore the dose-response relationship between BRI and new-onset stroke. During a 10-year follow-up, 626 participants developed new-onset stroke. After full adjustment for potential confounders, each 1-unit increase in BRI was associated with an 11% higher hazard of stroke (HR = 1.11, 95% CI: 1.03–1.20). Taking the low BRI tertile (Q1) as the reference group, the medium BRI tertile (Q2) and high BRI tertile (Q3) showed significantly elevated stroke risks (HR = 1.40, 95% CI: 1.12–1.76) and (HR = 1.47, 95% CI: 1.11–1.94), respectively. RCS analysis revealed a linear positive correlation between BRI and stroke risk ( P -overall < 0.01, P for nonlinearity = 0.915). Higher BRI was independently associated with new-onset stroke in patients with CKM syndrome stages 0–3, with a linear positive correlation between them. As a simple and non-invasive index, BRI may help identify individuals at higher stroke risk in this population, providing epidemiological evidence for clinical early intervention.