Association of the CHG index combined with obesity indices and incident cardiometabolic multimorbidity in a nationwide prospective cohort study.

Abstract

Cardiometabolic multimorbidity (CMM), the co-occurrence of at least two cardiometabolic diseases, poses a significant public health threat. The Cholesterol, High-density Lipoprotein, and Glucose (CHG) index is an emerging surrogate marker of insulin resistance, yet its association with CMM, particularly when integrated with obesity indices, remains unexplored.This prospective cohort study analyzed 6991 adults aged ≥ 45 years without baseline CMM from the China Health and Retirement Longitudinal Study (CHARLS). Multivariable Cox regression, Kaplan-Meier curves, and restricted cubic splines were used to assess associations between CHG-obesity composite indices and CMM risk. Predictive performance was evaluated using time-dependent receiver operating characteristic (ROC) analysis, Harrell's C-index, net reclassification improvement (NRI), and integrated discrimination improvement (IDI). A Fine-Gray competing-risks model, subgroup analyses, and sensitivity analyses were also conducted. Over a median follow-up of 9 years, 677 participants developed CMM. Each 1-unit increase in CHG-related indices was significantly associated with elevated CMM risk, with fully adjusted HRs ranging from 1.01 to 1.86. The Fine-Gray competing risk model confirmed this robust association. CHG-WC and CHG-WHtR yielded the highest C-index (both 0.701). All CHG-related indices significantly improved risk reclassification and discrimination relative to conventional risk factors (all continuous NRI and IDI, p < 0.05). Hypertension significantly modified the association. Sensitivity analyses confirmed robustness. CHG-composite indices are significantly associated with increased CMM risk and show potential as practical tools for risk stratification in middle-aged and older adults.