The Relationship Between Blood Eosinophil Levels and COVID-19 Mortality

Aim: COVID-19 is a global pandemic caused by severe acute respiratory syndrome (SARS-COV-2). The objective of this study is to determine the relationship between blood eosinophil levels and the severity and mortality of COVID-19. Methods: The data of 678 patients were retrospectively collected from the electronic database of a hospital by researchers between March 2020 and December 2021. This is a descriptive study, and no specific sampling method was employed. The data were evaluated based on three groups of patients (moderate, severe, and chronic). Eosinophil values within the first 24 hours following hospital admission were obtained. The data was analyzed through IBM SPSS Statistics (20.0) software. Parametric tests were used for the statistical evaluations when the normality assumptions were met. Mann-Whitney U was used for two independent groups and multivariate logistic regression analysis was used to identify the relations. p-value < 0.05 was considered statistically significant. Results: In our study, it was found that eosinophil levels did not have an effect on disease severity (p=0.941). The COVID-19 related mortality rate was 14.6%, and the rate of severe/critical disease progression was 27.3%. Upon examining hematological parameters, it was observed that critical cases had significantly higher NEU values (p=0.001) and PCT values (p=0.024). LYM (p=0.007), HGB (p=0.029), PLT (p=0.023), HCT (p=0.005), MCV (p=0.039), MCH (p=0.048), MCHC (p=0.001), and RDW (p=0.023) were significantly lower in the severe group. It was determined that age, HCT, MCV, MCHC, urea, uric acid, sodium and potassium parameters were not significant risk factors for mortality (p>0.05). A reduction in MCHC (OR: 0.996; p=0.007) and sodium (p=0.031) demonstrated a mitigating effect on disease severity. The predictive effect of other parameters was found to be statistically insignificant. Conclusion: The effect of eosinophil levels on the severity and mortality of COVID-19 has not been found, whereas a decrease in MCHC and sodium levels showed a mitigating effect on disease severity. Further research is needed to investigate the clinical significance of these indicators in COVID-19 patients.