Associations of C‐Reactive Protein–Triglyceride–Glucose Index With the Incidence and Progression of Cardiometabolic Multimorbidity in Middle‐Aged and Older Chinese Individuals: A Prospective Cohort Study From CHARLS

ABSTRACT Background Robust longitudinal studies evaluating the association between the C‐reactive protein–triglyceride–glucose index (CTI) and cardiometabolic multimorbidity (CMM) are scarce. To better understand the clinical value of the CTI, this study was conducted to explore the association of the CTI with CMM risk and progression, and to compare its predictive performance with indices incorporating central obesity. Methods This cohort study analyzed data from the China Health and Retirement Longitudinal Study spanning 2011–2020, including 9477 participants. The associations of the CTI, triglyceride–glucose (TyG), TyG–waist circumference (TyG–WC), and TyG‐waist‐to‐height ratio with CMM incidence were assessed using multivariable Cox regression. Predictive performance was compared using the area under the receiver operating characteristic curve (AUC), net reclassification index (NRI), and integrated discrimination improvement (IDI). Multi‐state models were used to analyze disease‐stage transitions. Results During follow‐up, 462 participants developed CMM. After full adjustment, a 1‐standard deviation increase in the CTI was associated with a 41% higher CMM risk (hazard ratio [HR]: 1.41, 95% confidence interval [CI]: 1.17–1.69). In direct comparison, TyG–WC showed the highest predictive AUC (0.704, 95% CI: 0.678–0.730). Adding the CTI to a conventional risk model significantly improved the NRI and IDI. Multistate modeling demonstrated that the CTI was associated with the progression from baseline health to diabetes mellitus, stroke, and heart disease, with a stronger association observed for diabetes mellitus (HR: 1.47, 95% CI: 1.36–1.60). Conclusions The CTI independently predicted CMM risk and progression. Although the TyG–WC index demonstrated superior predictive performance, the CTI remains a clinically convenient, blood‐based composite marker that captures the insulin resistance–inflammation pathway, offering a valuable tool for risk stratification.