Association of the C-reactive protein-triglyceride glucose index with incident hypertension across glycemic status: a longitudinal cohort study

The C-reactive protein-triglyceride glucose index (CTI) is a composite indicator that integrates systemic inflammation, lipid metabolism, and glucose metabolism. Previous studies have reported an association between CTI and incident hypertension, but evidence across different glycemic status remains limited. This longitudinal cohort study used data from the China Health and Retirement Longitudinal Study (CHARLS). Baseline data were obtained in 2011, and follow-up information was collected in 2013, 2015, 2018, and 2020. A total of 6435 participants aged 45 years or older without hypertension at baseline were included. CTI was calculated as 0.412 × ln(CRP [mg/L]) + ln(TG [mg/dL] × FPG [mg/dL]/2). Baseline glycemic status was classified as NGR, Pre-DM, or DM. Incident hypertension was defined as the first occurrence during follow-up of systolic blood pressure (SBP) ≥ 140 mmHg, diastolic blood pressure (DBP) ≥ 90 mmHg, self-reported physician-diagnosed hypertension, or current use of antihypertensive medication. Kaplan-Meier curves, log-rank tests, Cox proportional hazards models, restricted cubic spline analyses, subgroup analyses, and sensitivity analyses were used to evaluate the association between CTI and incident hypertension. During approximately 9 years of follow-up, 1705 participants developed incident hypertension. The cumulative incidence of hypertension increased across CTI quartiles. In the fully adjusted Cox model, each 1-unit increase in CTI was associated with an 18% higher risk of incident hypertension (HR = 1.18, 95% CI: 1.12–1.26, P < 0.001). The association was generally consistent across gender and age group, with no significant interactions by gender or age. After stratification by glycemic status, CTI was significantly associated with the risk of incident hypertension in the Pre-DM participants (HR = 1.19, 95% CI: 1.08–1.31, P < 0.001; Q4 vs. Q1: HR = 1.41, 95% CI: 1.15–1.72, P < 0.001), while the association in the NGR and DM participants did not reach statistical significance. Restricted cubic spline analyses supported an overall linear association between CTI and incident hypertension, and subgroup and sensitivity analyses yielded broadly consistent findings. CTI was associated with the risk of incident hypertension in the middle-aged and elderly population of China, and this association was generally consistent across different gender and age groups. A significant positive linear association between CTI and incident hypertension was observed among participants with Pre-DM. As a comprehensive indicator reflecting inflammation and glucose and lipid metabolism disorders, CTI may provide supplementary information for hypertension risk identification. Given the observational design, these findings require confirmation in further studies.