Secondary Eosinophilia A risk factor for prolonged hospitalization in severe COVID-19: A case control study

Abstract

BackgroundPrevious research has shown the potential benefit of eosinophilia in respiratory viral infections, which could suggest a milder clinical course and outcome for those with COVID-19 infection. However, there is mixed evidence regarding peripheral eosinophilia with regards to acute respiratory distress syndrome and there is little data in critically ill patients. MethodsTo evaluate the effect on clinical outcomes of developing peripheral eosinophilia during hospitalization for severe COVID-19 we performed a retrospective case control study comparing outcomes in patients who did and did not develop peripheral eosinophilia during hospitalization. ResultsPatients who developed peripheral eosinophilia during hospitalization had a more prolonged intensive care unit course, course of mechanical ventilation and hospital course. This was also seen in a sub-analysis of only patients who survived to hospital discharge. The two most identifiable causes of eosinophilia were related to antibiotics and secondary fungal or parasitic infections. Patients with an identifiable cause of eosinophilia had a more prolonged course of mechanical ventilation. Most cases had no cause identified. ConclusionOur findings support completing a work-up for newly developed peripheral eosinophilia since it may be an early sign of secondary infection, but it may be a result of medical treatments such as antibiotic therapy. Regardless of the cause, our data suggests secondary eosinophilia is associated with increased morbidity in critically ill patients.