Postnatal predictors of mortality and derivation of a novel risk score in congenital diaphragmatic hernia: A 21-year-single-center cohort study

Background Congenital diaphragmatic hernia is an important cause of neonatal morbidity and mortality, primarily because of pulmonary hypoplasia and pulmonary hypertension. Early postnatal risk stratification may improve prognostication and guide escalation of care. We aimed to identify early postnatal predictors of mortality and to derive a simple bedside mortality risk score for neonates with isolated congenital diaphragmatic hernia. Methods We conducted a retrospective cohort study of newborns with isolated congenital diaphragmatic hernia admitted to a tertiary-care NICU within 6 h of life between 2004 and 2025. Clinical and physiologic variables, including Day-1 oxygenation, inotrope requirement and preoperative pneumothorax, were extracted from the medical records. Receiver operating characteristic analysis and Firth penalized logistic regression were performed. A bedside score, the Neonatal Congenital Diaphragmatic Hernia Mortality Risk Score (NCMRS-6), was derived from early predictors and internally evaluated using bootstrap resampling. Results 66 newborns were included, of whom 52 (78.8%) survived to discharge. Non-survivors had a significantly higher Day-1 oxygenation index than survivors (median 64.0 vs 6.3; p < 0.001) and more frequent inotropic requirement (100% vs 40.4%; p < 0.001). Preoperative pneumothorax was also more common among non-survivors (46.2% vs 7.7%; p = 0.003). Day-1 oxygenation index alone showed excellent discrimination for mortality (area under the curve 0.945). The NCMRS-6, combining Day-1 oxygenation index tiers, inotrope requirement, and preoperative pneumothorax, demonstrated an area under the curve of 0.964 (95% confidence interval 0.894-1.000). A threshold of at least four points yielded 92.3% sensitivity and 90.4% specificity. Conclusions Day-1 oxygenation index, inotrope requirement and preoperative pneumothorax are important early predictors of mortality in isolated congenital diaphragmatic hernia. The NCMRS-6 is a simple bedside risk-stratification tool with promising discriminatory ability, but external validation is required before broader clinical application.