Predictive value of adding end-tidal CO₂ and perfusion index to NEWS2 for 30-day in-hospital mortality: a prospective study
摘要
This study aimed to evaluate whether integrating end-tidal carbon dioxide (ETCO₂) and perfusion index (PI) into the National Early Warning Score 2 (NEWS2) enhances its ability to predict 30-day in-hospital mortality in patients visitted to the emergency department (ED).
MethodsThis prospective, single-center cohort study was conducted between March 15 and May 15, 2025, in a tertiary ED. Adult patients requiring continuous monitoring were included. ETCO₂ and PI were measured upon admission and incorporated into the NEWS2 score using predefined thresholds. The primary outcome was 30-day all-cause in-hospital mortality. Model performance was assessed via ROC analysis, Brier score, Hosmer–Lemeshow test, decision curve analysis (DCA), and Net Reclassification Index (NRI).
ResultsA total of 375 patients were analyzed (mean age: 76.5 ± 7.6 years; 56.8% female), with a 30-day mortality rate of 5.9%. The base NEWS2 had an AUC of 0.804 (95%CI: 0.734–0.868), while the extended NEWS2 + ETCO₂ + PI model demonstrated a significantly higher AUC of 0.893 (95%CI: 0.824–0.944; p < 0.001). The optimal cut-off for the combined model was > 12, yielding 77.3% sensitivity and 90.9% specificity. It also showed superior calibration (Brier score: 0.039; HL p = 0.265) and the highest net clinical benefit between threshold probabilities of 0.22 and 0.45. NRI analysis showed a net reclassification improvement of 46.3%.
ConclusionThe integration of ETCO₂ and PI into the NEWS2 score significantly improves its predictive accuracy for short-term mortality. The combined model may contribute to earlier and more accurate identification of high-risk patients in emergency care settings.