High Dose Inhaled Corticosteroid Increased the Incidence of Idiopathic Pulmonary Fibrosis: Nationwide Population based Study

Background: Idiopathic pulmonary fibrosis (IPF) is a progressive disease found primarily in older people, with the use of systemic steroids linked to poor outcomes. However, role of inhaled corticosteroids (ICS) in IPF remains unclear. This This study investigated the association between ICS use and IPF risk using national insurance data, particularly in individuals with chronic airway diseases. Methods Utilising the National Health Insurance Service-National Sample Cohort database, our study included patients diagnosed with chronic obstructive pulmonary disease (COPD) or asthma. ICS exposure was assessed via treatment claims, and IPF cases were identified using broad and narrow criteria. We used inverse probability of treatment weighting (IPTW) with propensity scores for balanced covariate analysis. Results Of 57,456 patients (mean age: 55.9 years, 42.3% male), 16.5% used ICS and 83.5% did not. ICS users showed higher rates of broad (0.98 vs. 0.41 per 1,000) and narrow IPF (0.61 vs. 0.21 per 1,000) than non-users. Pre-IPTW, ICS use was associated with increased IPF risk; however, this was not significant post-IPTW. Post-IPTW, both continuous (broad adjusted hazard ratio [HR]: 1.03, 95% confidence interval [CI]: 1.02–1.04; narrow adjusted HR per 100 µg/day: 1.03, 95% CI: 1.01–1.04 post-IPTW) and high-dose ICS (≥ 1000 µg/day) (broad adjusted HR: 3.89, 95% CI: 1.61–9.41; narrow adjusted HR: 3.99, 95% CI: 1.19–13.41) use correlated with an elevated IPF risk. Subgroup analysis revealed an increased risk in medically aided. Conclusion High-dose ICS use may be associated with elevated IPF risk, especially in patients receiving medical aid.