Mortality Risk From COVID-19 Among Unvaccinated Subjects With Autoimmune Phenotypes of Interstitial Lung Disease

The impact of the severe acute respiratory syndrome-associated coronavirus 2 (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 coronavirus disease 2019 (COVID-19) pneumonitis. Our aim was to explore demographic and clinical differences between those with ILD who tested positive for the SARS-CoV-2 virus compared to those with ILD who did not.

In this retrospective cohort study, we identified adult, unvaccinated patients evaluated at the University of Chicago in 2020 who were enrolled in the ILD registry, and stratified by SARS-CoV-2 seropositive status. We then compared baseline clinical characteristics between SARS-CoV-2 seropositive and SARS-CoV-2 seronegative patients and assessed immunosuppressive therapy that the patient may have been on since ILD diagnosis. C-reactive protein and leukocyte subsets were evaluated at COVID diagnosis compared to the time of baseline ILD evaluation as were pulmonary function testing. 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.

Of the 309 individuals with ILD in our cohort, 6.8% (n=21) tested positive for SARS-CoV-2. Those who were SARS-CoV-2 positive were younger (57 years vs 66 years; P=0.002), had baseline higher total lung capacity (81% vs 73%, P=0.045), similar forced vital capacity (71% vs. 67%, P=0.37), and similar diffusion capacity of carbon monoxide (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 (connective tissue disease-ILD or interstitial pneumonia with autoimmune features) (62% vs 38%, P=0.029). Overall, the mortality hazard was highest among 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 unvaccinated adults who are younger, with autoimmune ILD, and on immunosuppressive therapy at higher risk. This suggests a need for COVID-19 vaccinations and therapy (inpatient and outpatient) for this group of patients at high risk for COVID-19. Larger studies are needed to fully explore the relationship between ILD and immunosuppressive therapy in COVID-19.