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Asthma as a predictor of outcomes in COVID-19 disease

1Sean N. Parker Center for Allergy and Asthma Research, Stanford University School of Medicine, 2Department of Medicine, Division of Hospital Medicine, Stanford University School of Medicine, 3Department of Medicine, Division of Pulmonary, Allergy & Critical Care Medicine, Stanford University School of Medicine; *corresponding author

Rationale: There has been conflicting initial data regarding the effect of comorbid asthma on severity of illness with COVID-19 disease. Multiple studies have demonstrated an increased prevalence of asthma among hospitalized patients, but more recent studies have not shown an increased risk of severe infection in patients with asthma. Furthermore, the Th2 inflammation associated with the allergic asthma subtype can downregulate ACE-2 expression providing a potential protective effect. Our objective is to understand the impact of asthma and eosinophilia as predictors of disease outcomes in patients at Stanford Hospital infected with SARS-CoV-2  

Methods:  SARS-CoV-2 RT-PCR positive patients tested at Stanford Hospital were identified and hospitalization status, asthma history, demographics, co-existing conditions, laboratory values and COVID-19 severity were determined.  Inpatients were defined as those patients hospitalized within 14 days of a positive test for SARS-CoV-2. Patients were excluded from further analysis if they had no other documented clinical history or were younger than 28 days. COVID-19 disease severity was designated according to the 5-point NIH COVID-19 treatment guidelines. 

Results:  From March 2 to September 30, 2020, 168,190 patients were tested for SARS-CoV-2 and 6,976 (4.1%) tested positive. 1,380 patients were excluded from further analysis. Of the remaining 5,596 patients, 605 required hospitalization. Of the 605 hospitalized patients, 100 had a pre-existing diagnosis of asthma. History of asthma was significantly associated with COVID-19-related hospitalization (p<0.001, adjusted odds ratio = 1.55, 95%CI = [1.21-1.97]) in multivariate analysis adjusted for age, sex, and ethnicity. Additionally, older age, male sex, and asthma were significantly associated with clinical severity of COVID-19 in hospitalized patients in multivariate analysis (p<0.05) with a trend for BMI >= 30 (p=0.06). For hospitalized patients with historical eosinophil counts (HEC) available for analysis, there was a trend toward higher HEC being protective for clinical severity (p = 0.075) stratified by age and asthma status.