Prognostic significance of the C-reactive protein–triglyceride–glucose index for all-cause and cardiovascular mortality in peritoneal dialysis: a multicenter cohort study

Chronic low-grade inflammation and insulin resistance (IR) frequently coexist in peritoneal dialysis (PD) and may drive excess mortality. The C-reactive protein-triglyceride-glucose index (CTI) integrates inflammatory (CRP) and metabolic (TyG) signals, but its prognostic value in PD is unknown. In a multicenter cohort of 2,240 Chinese PD patients, CTI was assessed 3 months after PD initiation and dichotomized at the median (5.09). Mortality outcomes were tracked through May 31, 2023. Analyses used Kaplan-Meier, Cox models (with and without propensity score matching [PSM]), prespecified subgroup analyses (sex, age, BMI, diabetes, hypertension), and restricted cubic splines (RCS) for dose-response. Incremental predictive value beyond established risk factors and single markers (hs-CRP, TyG) was evaluated using C-statistics, net reclassification improvement (NRI), and integrated discrimination improvement (IDI). There were 634 deaths (314 CVD). Cox regression analysis showed that a higher CTI was an independent risk factor for all-cause mortality and CVD mortality in PD patients. After full adjustment, compared with patients with CTI < 5.09, those with CTI ≥ 5.09 had a 34% higher all-cause mortality risk (HR 1.34, 95% CI 1.07-1.68) and a 39% higher CVD mortality risk (HR 1.39, 95% CI 1.01-1.93). RCS analysis revealed an approximately linear relationship between increased CTI and the elevated risk of both adverse clinical outcomes (P for nonlinearity > 0.05). The positive association between CTI and mortality was observed in both diabetic and non-diabetic subgroups (e.g., in diabetic patients: all-cause mortality HR 1.72, 95% CI 1.13-2.61; CVD mortality HR 2.11, 95% CI 1.21-3.68), with no statistically significant interaction by diabetes status (P for interaction > 0.05). Incremental predictive analyses showed that CTI had slightly higher C-indices than hs-CRP or TyG and provided only modest improvements in discrimination and reclassification. CTI independently and approximately linearly predicts all-cause and CVD mortality in PD, with consistent associations irrespective of diabetes status. It provides only modest incremental predictive value beyond hs-CRP and TyG, but its simplicity and cost-effectiveness support its potential use as a supplementary marker for risk stratification and individualized PD care.