Dose-response relationship of the C-reactive protein-triglyceride-glucose index with incident cardiometabolic multimorbidity ‒ A cohort study in middle-aged and elderly Chinese adults

Introduction: Background: China has the largest middle-aged and elderly population globally, with a rising prevalence of cardiometabolic multimorbidity (CMM) posing significant public health challenges. The C-reactive protein-triglyceride-glucose index (CTI) is recognized as an indicator of chronic low-grade inflammation, insulin resistance, and metabolic disorders. However, limited research exists on its association with CMM, particularly regarding dose-response relationships. This research examines the link between CTI and new-onset CMM in middle-aged and elderly Chinese individuals. Methods: data from the 2011 baseline and 2015 follow-up of the China Health and Retirement Longitudinal Study (CHARLS) were analyzed, involving 15,497 eligible participants. A multivariate logistic regression was conducted to evaluate the relationship between CTI and CMM risk, controlling for nine confounding variables. CTI was evaluated as a continuous variable (interquartile range, IQR) for linear analysis, and restricted cubic splines (RCS) tested potential non-linear relationships. Subgroup analyses examined the consistency of CTI effects across demographic and behavioral variables, while interaction tests evaluated potential interactions. Receiver operating characteristic (ROC) curve analysis assessed CTI's predictive performance. Results: over four years, 930 participants developed CMM (incidence rate: 7.5 %). Elevated CTI levels were strongly linked to a heightened risk of CMM. In the unadjusted model, each unit increase in CTI corresponded to a 63 % higher risk (OR = 1.63, 95 % CI: 1.49-1.79, p < 0.001). After adjustment, the risk remained elevated by 45 % (OR = 1.45, 95 % CI: 1.31-1.61, p < 0.001). Quartile analysis indicated an increased risk in the highest quartile (Q4) compared to the lowest quartile (Q1), with an odds ratio of 1.38 (95 % CI: 1.09-1.76, p = 0.007). RCS analysis showed no significant non-linear relationship (p = 0.832). CTI exhibited moderate predictive performance (area under the curve, AUC = 0.61). Conclusions: elevated CTI is linearly associated with increased CMM risk, indicating its potential as a predictive tool for CMM in middle-aged and elderly populations.