Association between the C-reactive protein–triglyceride–glucose index and incident cardiovascular disease in middle-aged and older adults with arthritis: a nationwide prospective cohort study with hospital-based cross-sectional replication

Background Arthritis encompasses heterogeneous joint and rheumatic conditions and is associated with increased cardiovascular disease (CVD) risk. The C-reactive protein–triglyceride–glucose index (CTI) integrates inflammatory and metabolic burden, but its association with CVD among adults with arthritis remains unclear. Methods Data from the China Health and Retirement Longitudinal Study (CHARLS) and an independent hospital-based cross-sectional replication cohort were analyzed. In the CHARLS, baseline CTI was assessed in 2,894 adults with self-reported physician-diagnosed arthritis or rheumatism. Cumulative CTI exposure (cumCTI) and exploratory two-time-point CTI level-change patterns were evaluated in 1,394 participants using Wave 3 in 2015 as the time origin. Cox regression, restricted cubic spline, subgroup, sensitivity, and exploratory predictive performance analyses were performed for incident CVD. In the hospital-based cohort, 7,960 participants were analyzed using logistic regression and spline analyses for prevalent CVD. Results In the CHARLS, 771 incident CVD events occurred in the baseline CTI analysis, and 300 occurred in the repeated-measures analyses. In fully adjusted models, baseline CTI was associated with incident CVD [hazard ratio (HR) = 1.251, 95% confidence interval (CI): 1.083–1.446, p = 0.002], with the highest risk in Q4 versus Q1 (HR = 1.587, 95% CI: 1.257–2.003; p for trend < 0.001). cumCTI was also associated with incident CVD (HR = 1.118, 95% CI: 1.025–1.220, p = 0.012), with higher risk in Q4 versus Q1 (HR = 1.504, 95% CI: 1.038–2.179; p for trend = 0.012). Compared with Cluster 1, both Cluster 2 and Cluster 3 were associated with higher CVD risk. In the hospital-based cross-sectional replication cohort, baseline CTI was associated with prevalent CVD recorded in hospital medical records. Exploratory predictive analyses showed modest discrimination for CTI [area under the curve (AUC) = 0.556, 95% CI: 0.529–0.583], and adding CTI to the basic model changed Harrell’s C-index from 0.615 to 0.618. Conclusion Higher CTI-related inflammatory-metabolic burden was associated with increased CVD risk in middle-aged and older adults with arthritis. CTI may provide complementary information for recognizing inflammatory-metabolic cardiovascular vulnerability in adults with arthritis, but its incremental predictive value was modest and requires further validation.