Association of the body roundness index with new-onset cardiovascular disease in middle-aged and older adults with and without diabetes: evidence from the China Health and Retirement Longitudinal Study

Among noncommunicable diseases, cardiovascular disease (CVD) is the leading cause of mortality and morbidity. In China, diabetes is renowned for its high incidence rate, and the body roundness index (BRI) is an emerging indicator for assessing obesity, particularly abdominal obesity. High BRI may lead to new-onset CVD events. However, the relationships between the BRI and new-onset CVD in individuals with or without diabetes remain unclear. Data for this analysis were extracted from the China Health and Retirement Longitudinal Study (CHARLS). Our research utilized a cohort that was meticulously assessed over a period from 2011 to 2018, encompassing a comprehensive follow-up of 17,708 participants. Ultimately, this study focused on a subset of 6,737 individuals aged 45 years or older. Methodological approaches include Cox regression, Kaplan-Meier survival analysis, restricted cubic splines (RCS) analysis, receiver operating characteristic (ROC) curve analysis, subgroup analysis, and mediation analysis to explore the relationships of interest. This study included 6,737 participants, all of whom were above the age of 45. Our findings revealed that within this demographic group, 1,481 (22.0%) patients experienced new-onset CVD. The Kaplan-Meier survival analysis further revealed that the group characterized by non-diabetes mellitus (Non-DM) had the lowest cumulative incidence of CVD compared with the diabetes mellitus (DM) group. Multivariate Cox regression revealed that in the fully adjusted model (Model 3) (HR = 1.122, 95% CI = 1.080 to 1.167), BRI was associated with the risk of CVD in the Non-DM group during the three-wave follow-up. RCS analysis revealed a positive, linear-like dose‒dependent relationship between BRI and new-onset CVD in Non-DM patients (P = 0.007, P for nonlinearity = 0.938). Smoking could affect the ability of the BRI to predict the incidence rate of CVD in the total population and in the population without diabetes (P interaction = 0.007). Moreover, the mediating effect of the BRI on new-onset CVD among diabetic patients was particularly pronounced in the long term, exceeding 4 years. Our findings demonstrate a significant association between the BRI and CVD risk in non-diabetic individuals, with diabetes influencing the incidence and risk of new-onset CVD in middle-aged and elderly Chinese populations through the BRI playing a mediating role. As an obesity indicator, the BRI provides a valuable tool for early detection and intervention of CVD. Not applicable.