Risk Factors for Preoperative Pneumothorax in Neonates with Isolated Left-Sided Congenital Diaphragmatic Hernia: an International Cohort Study.

Background: We aimed to investigate the clinical characteristics and outcomes of patients with isolated left-sided congenital diaphragmatic hernia (CDH) who developed preoperative pneumothorax and determine its risk factors. Methods: We performed an international cohort study of patients with CDH enrolled in the Congenital Diaphragmatic Hernia Study Group registry between January 2015 and December 2020. The main outcomes assessed included survival to hospital discharge and preoperative pneumothorax development. The cumulative incidence of pneumothorax was estimated by the Gray test. The Fine and Gray competing risk regression model was used to identify the risk factors for pneumothorax. Results: Data for 2858 neonates with isolated left-sided CDH were extracted; 224 (7.8%) developed preoperative pneumothorax. Among patients with a large diaphragmatic defect, those with pneumothorax had a significantly lower rate of survival to discharge than did those without. The competing risks model demonstrated that a patent ductus arteriosus with a right-to-left shunt flow after birth (hazard ratio [HR]: 1.78; 95% confidence interval [CI]: 1.21-2.63; p = 0.003) and large defects (HR: 1.65; 95% CI: 1.13-2.42; p = 0.01) were associated with an increased risk of preoperative pneumothorax. Significant differences were observed in the cumulative incidence of pneumothorax depending on defect size and shunt direction (p < 0.001). Conclusions: Pneumothorax is a significant preoperative complication associated with increased mortality in neonates with CDH, particularly in cases with large defects. Large diaphragmatic defects and persistent pulmonary hypertension were found to be risk factors for preoperative pneumothorax development. Level of Evidence: LEVEL III Retrospective Comparative Study.