Association between the C-reactive protein-triglyceride glucose index and incident hypertension across different blood pressure states: findings from the CHARLS

Background Hypertension is a major public health burden. Early detection of high-risk individuals is critical for prevention. The C-reactive protein-triglyceride glucose index (CTI), integrating insulin resistance and inflammation, may aid risk stratification, but its predictive value across different blood pressure (BP) states is unclear. Methods This prospective study included 5494 non-hypertensive adults from the China Health and Retirement Longitudinal Study (CHARLS), classified into normal BP (< 120/70mmHg) and elevated BP (120–139/70-89mmHg) groups. CTI was calculated from triglyceride-glucose (TyG) index and C-reactive protein (CRP). Multivariable logistic regression examined the association between CTI and incident hypertension over 7 years. Restricted cubic splines and receiver operating characteristic analyses were employed to examine the dose-response relationship and predictive performance. The incremental predictive value of CTI was assessed by net reclassification improvement (NRI) and integrated discrimination improvement (IDI). Results During the 7-year follow-up, 1772 participants (32.2%) developed hypertension. A significant, linear dose-response relationship was observed between CTI and hypertension risk. In the fully adjusted model, each 1-unit increase in CTI was associated with a higher risk of hypertension in both the normal BP group (odds ratio [OR] = 1.19, 95% confidence interval [CI]: 1.07–1.33) and the elevated BP group (OR = 1.12, 95% CI: 1.03–1.21). When analyzed by quartiles, the association was most pronounced in the highest quartile (Q4), with a stronger effect size observed in the normal BP group (Q4 vs. Q1: OR = 1.57, 95% CI: 1.15–2.16) than in the elevated BP group (OR = 1.36, 95% CI: 1.10–1.68). Adding CTI to conventional risk factors significantly improved risk prediction overall (NRI = 0.114, P < 0.001). A significant interaction was found with alcohol consumption in the elevated BP group (P for interaction = 0.009), indicating a stronger association among drinkers. Sensitivity analyses confirmed the robustness of all findings. Conclusions CTI is a robust predictor of future hypertension in both normal and elevated BP states, with a particularly strong effect in normotensive individuals. Its integration into clinical practice could enhance early-risk stratification for primordial and primary prevention.