New Simplified White Blood Cells Score Improves Mortality Prediction in Severe COVID-19 Patients

Background: An unfavorable course of SARS-CoV-2 infection can lead to significant morbidity and mortality. The study aimed to develop a simple, accessible, and reliable tool to anticipate the poor results among COVID-19 pneumonia patients. Methods: This retrospective cohort study involves 306 individuals with severe COVID-19 pneumonia enrolled between March 2021 and June 2021. Each patient had confirmed SARS-CoV-2 infection and required oxygen therapy. Differential blood count and serum CRP were taken on admission day. Medical data were collected from the hospital's information system. Results: Of 306 patients (133 females, 173 males, aged 66.3 ± 15.2 years), 105 (34.3%) died. Counts of neutrophils, lymphocytes, and eosinophils differed significantly between survivors and deceased (p < 0.001; p = 0.002; p = 0.009, respectively) and had substantially differentiating properties in ROC analysis. Built with the counts of neutrophils, lymphocytes, and eosinophils, the White Blood Cell Score (WBCS) was developed. WBCS robustly predicted mortality (OR = 2.821; CI: 2.037-3.906; p < 0.001) in the investigated population. Cumulative risk of death according to WBCS (ranging from 0 to 3 points) was as follows: 0 points-10.9%, 1 point-23.5%, 2 points-33.1%, 3 points-34.1%. Conclusions: Based on differential blood count, the proposed WBCS is easy to use and can be helpful in predicting mortality among severe COVID-19 patients.