Association between C-reactive protein-triglyceride-glucose index and one-year all-cause mortality in patients with cardiometabolic multimorbidity

Introduction Cardiometabolic multimorbidity (CMM) is increasingly prevalent among middle-aged and older adults. The C-reactive protein-triglyceride glucose index (CTI), a novel biomarker integrating inflammation and insulin resistance (IR), has been linked to CMM prevalence and incidence. However, its association with all-cause mortality in CMM patients remains unclear. This study aimed to investigate the relationship between CTI and one-year mortality in CMM patients. Methods The retrospective-prospective cohort study enrolled 7,220 participants between January 2022 and December 2024. The primary endpoint was all-cause mortality within 365 days of admission. Mortality was verified in January 2026 through electronic medical record (EMR) review and telephone follow-up, with no loss to follow-up. Patients were categorized into four groups according to the quartiles of the CTI. We employed least absolute shrinkage and selection operator (LASSO) regression to identify key predictors. Cox proportional hazards models, Kaplan–Meier curves, restricted cubic spline analyses, and ROC curves were employed to evaluate the associations of CTI with the mortality in CMM patients. Additionally, subgroup analyses were conducted to explore potential effect modifiers. Results This study included 7,220 individuals with CMM. During the one-year follow-up, 537 (7.44%) deaths occurred, with elevated CTI levels showing a significant association with increased risks of all-cause mortality. Per 1-SD increase in CTI corresponded to a 17% higher mortality risk (HR = 1.17, 95% CI 1.07–1.29), while patients in the highest CTI quartile exhibited a 75% elevated risk vs. the lowest quartile (HR = 1.75, 95% CI 1.30–2.37). Our results suggested a positive association between CTI and CMM mortality, with risk increasing from Q1 to Q3 and plateauing in Q4. Additionally, CTI alone yielded an AUC of 0.639, the base model yielded an AUC of 0.828; the addition of CTI increased the AUC to 0.833. Conclusion Our analysis revealed that elevated CTI levels were significantly associated with all-cause mortality in CMM patients. As a clinically practical marker, CTI may serve as an exploratory risk-stratification marker in CMM patients and its clinical utility remains to be confirmed in prospective studies.