The diagnostic value of neutrophil to lymphocyte ratio in determining the severity of COVID-19

Background: Changes in hematological parameters play a role in the pathogenesis of coronavirus disease 2019 (COVID-19). We aimed to investigate the significance of neutrophil-lymphocyte ratio (NLR) and hematologic parameters in determining the severity of COVID-19. Methods: This retrospective cross-sectional study was conducted on adult patients diagnosed with COVID-19 in two pandemic hospitals between 01, April, and 01, July 2020. Using the COVID-19 diagnostic criteria of the world health organization (WHO), the patients were divided into two groups as severe and non-severe. Demographic and clinical characteristics, white blood cell (WBC), neutrophil, lymphocyte and platelet counts, and NLR of all patients were examined at the first admission. Multivariate analyzes were performed to determine the independent predictive data and ROC analysis to test the diagnostic accuracy of the hematological parameters. Results: Of the 381 patients included in the study, 42 (11%) had severe COVID-19 infection. While the mean NLR was 7.61±7.48 in patients with severe COVID-19, the mean NLR of non-severe patients was 2.97±2.37 (95% CI: 2.294 to 6.984, p<0.001). Long duration of hospital stay, elevated NLR ratio, female gender were predictive variables of severe COVID-19 cases (OR =0.833, 95% CI: 0.744 to 0.934, p=0.002; OR=0.195, 95% CI: 0.057 to 0.6731, p=0.010; OR=0.664, 95% CI: 0.501 to 0.881, p=0.005, respectively). In ROC analysis, NLR ratio had 2.625 optimum cut-off value, 60% specificity (95% CI: 54.7 to 65.4), 86% sensitivity (95% CI: 71.5 to 94.6), positive likelihood ratio (PLR) of 4.2 (95% CI: 2.0 to 8.9) and negative likelihood ratio (NLR) of 0.46 (95% CI: 0.4 to 0.6) for severe COVID-19 cases. Conclusion: The results of this study revealed that there might be a relationship between elevated NLR and severity in COVID-19 cases. IMC J Med Sci 2022; 16(1): 001 *Correspondence: Dr. Umut Gulacti, Adiyaman University Training and Research Hospital, Emergency Medicine, Adiyaman, Turkey. E-mail: umutgulacti@gmail.com