Predictive Value of C-Reactive Protein/Triglyceride-Glucose Index on the All-cause Mortality among Middle-Aged and Older Chinese Adults: A Prospective Cohort Study from CHARLS

The rising prevalence of metabolic syndrome in Chinese adults ≥ 45 years reflects rapid socioeconomic and lifestyle changes. C-reactive protein (CRP) and triglyceride-glucose (TyG) index, biomarkers of chronic inflammation and insulin resistance, jointly drive metabolic dysregulation. However, their combined index (CTI/CRP-TyG Index) remains understudied in mortality prediction. This prospective cohort included 9,055 participants from China Health and Retirement Longitudinal Study (CHARLS) database. CTI was categorized into quartiles (Q1-Q4). Kaplan-Meier curves and Cox regression (adjusting for sociodemographics, lifestyle, and clinical factors) were used in survival analysis. Restricted cubic splines (RCS), subgroup analysis and ROC/NRI/IDI evaluated CTI-mortality associations and predictive model performance. During follow-up, 221 deaths occurred, showing declining survival rates with higher CTI quartiles (98.50%→95.63%, p < 0.001). The highest CTI quartile had 3.48-fold mortality risk (HR = 3.48, 95%CI:2.25–5.40, p < 0.001). Subgroup analysis revealed stronger CTI-mortality associations in participants aged ≥ 55, primary education, or cardiovascular history, with overall HR = 2.76 (95%CI:2.20–3.47, p < 0.001). RCS and ROC analysis demonstrated that CTI quartiles linearly correlated with mortality (p < 0.001), and improved the efficiency of predictive models (AUC:0.849 vs 0.829, p = 0.008; NRI = 0.425, IDI = 0.029, p < 0.05). CTI quartiles increase elevated mortality of Chinese adults over 45, driven by CRP/triglyceride/glucose synergy. Targeting these biomarkers may lower mortality of metabolic-aging populations.