Background: 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 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 Chicago in 2020 with a multidisciplinary diagnosis of ILD, and stratified by detection of the SARS-CoV-2 virus presence or absence on PCR. Demographic data, laboratory values, and pulmonary function testing values were obtained at time of ILD diagnosis. Immunosuppressive therapies received since ILD diagnosis were assessed, as was mortality. 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: Of the 309 individuals with ILD in our cohort, 6.8% (n=21) tested positive for SARS-CoV-2. Those that were SARS-CoV-2 positive were younger (57 yrs vs 66 yrs; P=0.002), had baseline higher TLC (81% vs 73%, P=0.045), similar FVC (71% vs. 67%, P=0.37), and similar DLCO (71% vs. 62%, P=0.10) at baseline. Among patients with ILD and COVID-19, 67% had received immunosuppressive therapies compared to 74% of those with ILD without COVID-19. Those with ILD and COVID-19 were also more likely to have had a diagnosis of autoimmune related-ILD (CTD-ILD or IPAF) (62% vs 38%, P=0.029), and were more frequently hypoxemic (SpO2 ≤ 92%; 4% vs 19%; P=0.012) at ILD diagnosis than those without COVID-19. The majority of patients (62%) with COVID-19 had received lymphocyte-depleting immunosuppressive therapy prior to infection. Overall, the mortality hazard was highest amongst unvaccinated subjects with autoimmune related-ILD who had COVID-19 (OR=9.6, 95%CI=1.7-54.0; P=0.01).
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.