The relationship between C-reactive protein-triglyceride-glucose index and cardiovascular disease: insights from the China health and retirement longitudinal study (CHARLS)

OBJECTIVE: Chronic inflammation and metabolic dysregulation are key drivers of cardiovascular disease (CVD). Although the triglyceride-glucose (TyG) index and C-reactive protein (CRP) have each been associated with cardiovascular risk, their combined use as a C-reactive protein-triglyceride-glucose index (CTI) may improve risk prediction. This study aimed to investigate the association between the CTI and CVD, with particular focus on various population subgroups, and to evaluate its predictive capacity for incident CVD. METHODS: This investigation utilized data from the China Health and Retirement Longitudinal Study (CHARLS) cohort, which included 8084 middle-aged and older participants. The association between the CTI and the incidence of CVD was examined using Kaplan-Meier survival analysis, multivariable Cox proportional hazards regression models, and restricted cubic splines (RCS). The predictive performance of CTI was evaluated by receiver operating characteristic (ROC) curve analysis, along with net reclassification improvement (NRI) and integrated discrimination improvement (IDI). Furthermore, subgroup and sensitivity analyses were performed to test the robustness of the results. RESULTS: During follow-up, 2,133 participants (26.39%) developed CVD. After adjustment for potential confounders, each one-unit increase in the CTI was associated with a 44% higher risk of CVD (HR = 1.44, 95% CI: 1.17-1.78). Compared with the lowest quartile, higher quartiles of CTI were associated with a stepwise increase in risk (HR = 1.23, 1.29, and 1.40; P for trend < 0.001). Subgroup analyses indicated stronger associations among participants aged 45-60 years and those who were married. RCS analyses further supported an overall linear relationship between CTI and CVD risk. Moreover, the CTI index improved reclassification metrics (NRI/IDI) and discriminative ability (AUC). Sensitivity analyses corroborated these primary findings. CONCLUSION: The CTI, as a composite biomarker reflecting integrated metabolic and inflammatory status, demonstrated a significant positive association with CVD risk. Furthermore, this association exhibited variations across age groups and marital status, indicating the potential utility of CTI as a novel and clinically relevant biomarker for CVD risk stratification.