Risk of diaphragmatic hernia in patients with spontaneous pneumothorax

BACKGROUND: Few studies have implied the incidence of diaphragmatic hernia (DH) after spontaneous pneumothorax (SP) with unknown mechanisms. The current study aimed to identify whether there is an association between the DH and SP. METHODS: We selected 46,897 patients with SP (SP cohort) and 46,897 without SP (non-SP matched cohort) from the National Health Insurance Database. Patients were frequency matched according to age, sex, and index year. The incidence of DH and its association with SP were assessed after stratifying different characteristics and comorbidities. Statistical analysis including chi-square test, t-test, cox proportional hazard model, and Kaplan–Meier method were used. RESULTS: The results suggested there were significant associations between SP and DH, especially in the subgroup of patients with older age (aged 40–64 years: 2.61-fold in adjusted hazard ratio (aHR), 95% confidence interval (CI): 1.27–5.36; aged > 65 years: 1.97-fold in aHR, 95% CI 1.43–2.71), male sex (2.11-fold in aHR, 95% CI 1.56–2.85), hypertension (2.05-fold in aHR, 95% CI 1.30–3.23), diabetes mellitus (2.58-fold in aHR, 95% CI 1.37–4.86), and smoking-related disease (1.86-fold in aHR, 95% CI 1.28–2.71). The SP cohort has significantly correlated with DH within 5-year follow-up (< 2 years: 3.22-fold in aHR, 95% CI 2.10–4.94; 2–5 years: 1.70-fold in aHR, 95% CI 1.05–2.75). CONCLUSIONS: The SP cohort had a higher incidence of DH than the non-SP matched cohort. A prospective study of indications based on the findings of the current research should be performed.