A study to evaluate the role of eosinophil count as a prognostic marker for assessing the outcome in patients with COVID-19 infection.

Background and Objectives: The triaging of COVID-19 patients is of paramount importance to plan further management. There are several clinical and laboratory parameters that help in categorizing the disease severity, triaging, and prognostication. Little is known about the prognostic significance of eosinopenia in predicting the severity of COVID-19 from large hospital data, especially from low- and middle-income countries. The objective of this study is to evaluate the level of eosinopenia as an early prognostic marker for assessing the outcomes in COVID-19 patients and to assess the superiority of eosinopenia as a prognostic marker for assessing the outcomes in COVID-19 patients compared to lymphopenia and neutrophil-to-lymphocyte ratio (NLR). Methods: The study was carried out in a tertiary care hospital. A retrospective longitudinal approach was adopted wherein the hospital records of COVID-19 patients were analyzed. In our study, two separate groups of patients were included for analysis to describe the association between initial eosinophil counts of the patients and the clinical outcomes. In the first group, the disease severity in terms of clinical and radiological parameters was compared in patients of COVID-19 presenting with and without the presence of initial eosinopenia. Commonly used markers for triage, namely lymphopenia and NLR, were compared with the presence of initial eosinopenia among the patients who progressed to moderate and severe disease. In the second group, an analysis of eosinopenia was made among the patients who succumbed to the illness. Results: It was seen that 29.6% of patients with eosinopenia had moderate and severe disease compared to those without eosinopenia where only 10.8% had moderate disease, none had severe disease. It was seen that 19.7% of patients with eosinopenia but no lymphopenia had more severe disease compared to patients with lymphopenia but no eosinopenia where 10.8% of the patients had moderate disease, none had severe disease. In patients younger than 60 years who died of COVID-19, it was found that initial eosinopenia was found in 86%, whereas a high NLR >17 was seen in only 25.6% of patients who died, thus implying that is eosinopenia is an important marker of disease severity in COVID-19. Conclusions: Eosinopenia is an important parameter in the evaluation of COVID-19 and the presence of it should alert the clinicians regarding the further progression of the disease. It is not only an important marker but also an early marker for severe disease.