Association of Body Roundness Index with Cardiovascular Diseases in Middle-Aged and Older Chinese Adults with Cardiovascular-Kidney-Metabolic Syndrome Stage 0-3: Evidence from the CHARLS Study

Objective This study aimed to evaluate the association between the body roundness index (BRI) and the risk of incident cardiovascular disease (CVD) among middle-aged and older Chinese adults in cardiovascular-kidney-metabolic (CKM) syndrome stages 0–3. Methods A total of 7,566 participants from the China Health and Retirement Longitudinal Study (CHARLS), free of baseline CVD and classified as CKM stage 0–3, were included. Multivariable Cox models, restricted cubic splines, mediation analyses, and receiver operating characteristic (ROC) curves were used to assess associations, dose-response relationships, potential mediators, and predictive performance. Results During a maximum 9.0-year follow-up, 1,836 incident CVD cases were documented. Each 1-unit increase in BRI was associated with a 15.4% higher risk of CVD (HR: 1.154, 95% CI: 1.112–1.199), 13.4% for heart disease, and 18.7% for stroke. Participants in the highest BRI quartile had significantly elevated risks compared to the lowest quartile. A linear dose-response relationship was observed. Hypertension and dyslipidemia mediated 10.8% and 11.6% of the association, respectively. BRI demonstrated superior predictive ability for CVD (AUC=0.71) compared to body mass index (BMI) and A Body Shape Index (ABSI). Conclusion Higher BRI levels are independently associated with increased CVD risk in CKM stages 0–3, with a dose-response relationship. BRI outperforms BMI and ABSI in risk prediction, partially mediated by hypertension and dyslipidemia, supporting its use for early CVD stratification in this population.