C-reactive protein-triglyceride glucose index and its dynamic trajectories on all-cause mortality in critically ill children: a longitudinal, retrospective cohort study.

BACKGROUND: CTI has prognostic value in adults, but its utility and trajectory significance in critically ill children remain unexplored. METHODS: This retrospective cohort study included critically ill children aged 29 days to 18 years from the Pediatric Intensive Care Database. Baseline CTI and longitudinal CTI trajectories were evaluated for 30-day all-cause mortality using Cox regression and latent class growth mixed model. RESULTS: Among 3533 children, each interquartile range increase in baseline CTI was independently associated with a 50% higher risk of mortality (aHR = 1.50, 95% CI: 1.23-1.84). CTI demonstrated superior discrimination compared with TyG or CRP alone and significantly improved PRISM model performance. A CTI cutoff of 10.42 identified patients with a twofold higher mortality risk (aHR = 2.05, 95% CI: 1.46-2.88). Importantly, this study further identified distinct CTI trajectory patterns, with low-stable and U-shaped trajectories showing significantly lower mortality risk than the high-stable trajectory. CONCLUSIONS: This is the first study to demonstrate the dual prognostic value of both baseline CTI and longitudinal CTI trajectories in critically ill children, highlighting CTI as a simple and dynamic tool for mortality risk stratification in pediatric critical care. IMPACT: This study is the first to validate the C-reactive protein-triglyceride glucose index (CTI) as a prognostic biomarker in critically ill children. A clinically practical CTI cutoff value of 10.42 identified children with approximately twofold higher mortality risk. Longitudinal trajectory analysis revealed that persistently high CTI trajectories were associated with the worst prognosis, whereas low-stable and U-shaped trajectories were linked to lower mortality risk. CTI provides a simple, readily available tool for both static and dynamic risk stratification in pediatric critical care.