Association between the use of statins and risk of interstitial lung disease/idiopathic pulmonary fibrosis: time-dependent analysis of population-based nationwide data

Background We aimed to study whether statin use is associated with lowering the development of interstitial lung disease (ILD) and idiopathic pulmonary fibrosis (IPF). Methods The study population was the Korean National Health Insurance Service-Health Screening Cohort. ILD and IPF cases were identified using diagnosis codes (J84.1 for ILD and J84.1A as a special code for IPF) based on the International Classification of Diseases, 10th Revision. The study participants were followed up from 1 January 2004 to 31 December 2015. Statin use was defined by the cumulative defined daily dose (cDDD) per 2-year interval and participants were categorised into never-users, <182.5, 182.5–365.0, 365.0–547.5 and ≥547.5 by cDDD. A Cox regression was used to fit models with time-dependent variables of statin use. Results Incidence rates for ILD with and without statin use were 20.0 and 44.8 per 100 000 person-years, respectively, and those for IPF were 15.6 and 19.3 per 100 000 person-years, respectively. The use of statins was independently associated with a lower incidence of ILD and IPF in a dose–response manner (p-values for trend <0.001). ILD showed respective adjusted hazard ratios (aHRs) of 1.02 (95% CI 0.87–1.20), 0.60 (95% CI 0.47–0.77), 0.27 (95% CI 0.16–0.45) and 0.24 (95% CI 0.13–0.42) according to the increasing category of statin use compared with never-users. IPF showed respective aHRs of 1.29 (95% CI 1.07–1.57), 0.74 (95% CI 0.57–0.96), 0.40 (95% CI 0.25–0.64) and 0.21 (95% CI 0.11–0.41). Conclusion A population-based cohort analysis found that statin use is independently associated with a decreased risk of ILD and IPF in a dose–response manner.