Abstract
BACKGROUND/AIMS: The impact of coronavirus disease 2019 (COVID-19) on severe exacerbation and mortality in interstitial lung disease (ILD) is unclear. In this study, we evaluate the risk of severe exacerbation and mortality in individuals with ILD following COVID-19. METHODS: Using the Korean National Health Insurance claim-based database, we compared the incidence and risk of severe exacerbation and mortality in individuals with ILD who survived at least one month after COVID-19 (COVID-19 cohort, n = 359) and 1:3 age, sex, and body mass index-matched individuals with ILD who did not have COVID-19 (controls, n = 1,077) between October 8, 2020, and August 30, 2021. RESULTS: During a mean follow-up of 7.4 months, the COVID-19 cohort had a higher risk of severe exacerbation compared to controls (aHR 2.26, 95% CI 1.38-3.69). During a mean follow-up of 19.6 months, the COVID-19 cohort had a higher risk of death (aHR 2.79, 95% CI 1.63-4.79) compared to controls. When considering COVID-19 severity, the severe COVID-19 group had a higher risk of severe exacerbation and death compared to controls, while the non-severe COVID-19 group did not show increased risk of severe exacerbation or death. In analyses based on ILD subtype, individuals with idiopathic pulmonary fibrosis in the COVID-19 cohort had the highest risk of severe exacerbation and death. CONCLUSION: Previous severe COVID-19 was associated with worse clinical outcomes in individuals with ILD, especially in patients with idiopathic pulmonary fibrosis.