ABSTRACT
Introduction: The impact of the SARS-CoV-2 virus on patients with interstitial lung disease (ILD) remains poorly understood. As patients with ILD often have severe underlying lung parenchymal involvement, and immunosuppressive therapy is common in this population, they are presumed to be at high risk for severe COVID-19 pneumonitis. We investigated clinical differences between those with ILD who tested positive for the SARS-CoV-2 virus compared to those with ILD who did not, and explored the relationship with use of immunosuppressive therapy. Methods: In this retrospective cohort study, we identified patients evaluated at the University of Chicagoin 2020 who were enrolled in the ILD registry, and stratified by SARS-CoV-2 seropositive status. We then compared baseline clinical characteristics between SARSCoV- 2 seropositive and SARS-CoV-2 seronegative patients and assessed immunosuppressive therapy at time of COVID diagnosis. C-reactive protein (CRP) and leukocyte subsets were evaluated at COVID diagnosis compared to time of baseline ILD evaluation. Variable comparisons were determined by two-sided t-tests, or chi-square tests as appropriate, and logistic regression models were fitted to assess the odds of death from COVID-19 using generalized linear models with maximum-likelihood estimation.Results: 309 subjects with ILD were included in this analysis, of which 21 patients had a confirmed SARS-CoV-2 infection (6.8%). Patients with SARS-CoV-2 were younger (55 yrs vs. 66 yrs;P=0.006) , had similar baseline leukocyte counts (9.4 vs 8.6;P=0.569) and demonstrated a trend towards a lower CRP (4.9 vs9.3;P=0.068) when compared to those without. Subjects with SARS-CoV-2 and ILD were more likely to have a diagnosis of autoimmune related-ILD (CTD-ILD or IPAF) (71% vs 39%;P=0.004), higher baseline lymphocyte fraction of circulating leukocytes (29% vs. 21%;P=0.025);greater prevalence of honeycomb fibrosis (43 vs. 21%;P=0.044), and were more frequently hypoxemic [SpO2<92%] (20% vs. 4%;P=0.009) at ILD diagnosis. The majority (62%) of patients with SARS-CoV-2 virus were on immunosuppressive therapy at time of diagnosis. Although, CRP titers were higher at diagnosis of COVID pneumonitis than at ILD diagnosis (52mg/L vs. 5mg/L;P=0.006), the lymphocyte fraction of circulating leukocytes did not differ (24% vs 28%;P=0.52)(Fig.1). Further, subjects with ILD and SARS-CoV-2 had higher odds of death than those without SARS-CoV-2 (OR=24, 95% CI-4-152;P<0.001). Conclusion: SARS-CoV-2 is prevalent in ILD, and may put those who are younger, with autoimmune ILD, and on immunosuppressive therapy at higher risk. Larger studies are needed to fully explore the relationship between ILD and immunosuppressive therapy in COVID-19. .