Association of trajectories and cumulative exposure of modified cardiometabolic index with cardiovascular disease in middle and older adults

The Modified Cardiometabolic Index (MCMI), a new composite indicator, combines glucose, lipid metabolism, and fat accumulation levels and serves as an alternative predictor of cardiovascular disease (CVD). However, no prospective evidence exists linking long-term MCMI change patterns to Incident CVD. This study evaluated the association and dose–response relationship between MCMI change patterns and cumulative MCMI (cumMCMI) with incident CVD in middle-aged and older adults from the China Health and Retirement Longitudinal Study (CHARLS, N = 4324) and the English Longitudinal Study of Ageing (ELSA, N = 2707), and compared its predictive ability with cumulative triglyceride-to-glucose (TyG) index. Using K-means and group-based trajectory models, three MCMI change patterns were identified: stable low, moderate, and high-level groups. The Cox model adjusting for covariates revealed that moderate and high-level groups in both cohorts were associated with a significant increased incident CVD risk compared to stable low-level (CHARLS adjusted HR for high-level = 1.33, 95% CI 1.04 to 1.70; ELSA adjusted HR = 1.96, 95% CI 1.08 to 3.56). Restricted mean survival time (RMST) analysis revealed that participants with higher MCMI had a significantly shorter mean CVD-free survival time over the next 5 years (RMST = -0.070, 95% CI -0.119 to -0.021) in CHARLS. Restricted cubic spline (RCS) analysis demonstrated a significant positive linear association between cumMCMI and increased incident CVD risk. Furthermore, time-dependent ROC analyses across 5- to 6-year horizons indicated that cumulative MCMI exhibited slightly better discrimination for incident CVD than cumulative TyG in both CHARLS (AUC = 0.618 vs. 0.599, P = 0.005) and ELSA (AUC = 0.668 vs. 0.633, P = 0.004). These findings indicate that persistently elevated MCMI change patterns and higher cumulative MCMI exposure are independently associated with an increased risk of incident CVD and reduced CVD-free survival among middle-aged and older adults. Compared with cumulative TyG, cumulative MCMI demonstrated slightly better discrimination for CVD risk. Tracking dynamic changes in MCMI over time may serve as an informative, non-invasive surrogate approach to aid in long-term cardiometabolic risk stratification in primary care.