Association between C-reactive protein-triglyceride glucose index and all-cause mortality and premature death: a joint analysis based on case data from the Central Hospital of Shaoyang and CHARLS database.

Background: This study systematically investigates the relationship between C-reactive protein-triglyceride glucose index (CTI) and the risks of all-cause and premature mortality. Methods: A total of 10,350 participants from the China Health and Retirement Longitudinal Study (CHARLS) (2011-2020) and 1,842 participants from the Central Hospital of Shaoyang (CHSY) (2019-2024), aged 45 years or older, were included. CTI was calculated based on C-reactive protein (CRP) and the triglyceride-glucose index (TyG). Cox proportional hazard models were employed to assess the association between CTI and all-cause mortality and premature death. Restricted cubic spline (RCS) analysis were used to explore potential non-linear relationships. Subgroup and sensitivity analyses were conducted to verify the robustness of the findings. In addition, the concordance index (C-index) evaluate the risk differentiation ability of the different indicators. Results: In the CHARLS cohort, each one-standard-deviation increase in the CTI was associated with an elevated risk of mortality (all-cause mortality: HR = 1.86; premature death: HR = 2.10). Similar results were observed in the CHSY cohort (all-cause mortality: HR = 1.84; premature death: HR = 2.37). Restricted cubic spline analysis revealed a non-linear dose-response relationship in the CHSY dataset. Subgroup analyses indicated that this association was more pronounced among males, individuals with lower education levels, and those without hypertension. Sensitivity analyses yielded consistent results, supporting the robustness of the findings. In terms of predictive performance, C-index analysis demonstrated that the discriminative ability of CTI was slightly superior to that of the TyG index (mostly ranging between 0.61 and 0.65), suggesting its potential utility in risk prediction. Conclusion: This multicenter pooled analysis provides evidence that elevated CTI is an independent risk factor for all-cause and premature mortality, supporting its potential utility in public health screening and clinical risk assessment. However, further prospective studies are warranted to validate its clinical applicability.