Eosinophilia Is Associated with Improved COVID-19 Outcomes in Inhaled Corticosteroid-Treated Patients

ABSTRACT

Background

In addition to their proinflammatory effect, eosinophils have anti-viral properties. Similarly, inhaled corticosteroids (iCS) were found to suppress coronavirus replication in-vitro and were associated with improved outcomes in coronavirus disease 2019 (COVID-19). However, the interplay between the two and its effect on COVID-19 needs further evaluation.

Objective

Determine the association between pre-existing blood absolute eosinophil counts (AEC), iCS and COVID-19-related outcomes.

Methods

We analyzed data from the Cleveland Clinic COVID-19 Research Registry (April 1, 2020 to March 31, 2021). Of the 82,096 individuals who tested positive, 46,397 had blood differential cell counts obtained before SARS-CoV-2 testing dates. Our endpoints included need for hospitalization, admission to the intensive care unit (ICU) and in-hospital mortality. The effect of eosinophilia on outcomes was estimated after propensity weighting and adjustment.

Results

Of the 46,397 patients included in the final analyses, 19,506 had pre-existing eosinophilia (>0.15 x10³ cells/μL), 5,011 received iCS, 9,096 (19.6%) were hospitalized, 2,129 (4.6%) required ICU admission, and 1,402 (3.0%) died during index hospitalization. Adjusted analysis associated eosinophilia with lower odds for hospitalization (OR [95% CI]: 0.86 [0.79; 0.93]), ICU admission (OR [95% CI]: 0.79 [0.69; 0.90]), and mortality (OR [95% CI]: 0.80 [0.68; 0.95]) among iCS-treated, but not in untreated patients. The correlation between AEC and the estimated probability of hospitalization, ICU admission and death was non-linear (U-shaped) among patients not treated with iCS, and negative in treated patients.

Conclusion

The association between eosinophilia and improved COVID-19 outcomes depends on iCS. Future randomized controlled trials are needed to determine the role of iCS and its interaction with eosinophilia in COVID-19 therapy.