The importance of neutrophil-to-lymphocyte, platelet-to-lymphocyte, and neutrophil-to-platelet ratios as predictive indicators of severity in COVID-19 Patients

Background: COVID-19 is a global pandemic caused by Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2). Various clinical and hematological findings have been identified that can predict disease severity. This study aims to investigate the roles of the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and neutrophil-to-platelet ratio (NPR) in predicting the severity of COVID-19 infection. Methods: In this analytical cross-sectional single-center study, after obtaining Ethics Committee clearance, patients with laboratory-confirmed COVID-19 infection admitted during their first two weeks of illness were included. NLR, PLR, and NPR were derived from the CBC reports. These ratios were compared in each clinical category group to assess the severity. Results: The total number of cases was 160, with a mean age at diagnosis of 56 years. The proportion of males was slightly higher (54.4%) than that of females (45.6%). The proportion of Category C patients (66.9%) was higher than that of Category B (25%) and Category A (8.1%) patients. It was found that NLR, PLR, and NPR ratios had a statistically significant association with severe COVID-19 infection, suggesting they can be used to differentiate between Category C and Category A or B. NLR is a better predictor of the severity of COVID-19 disease than PLR and NPR. Conclusion: NLR, PLR, and NPR ratios can serve as predictive markers of disease severity in COVID-19 infections. Among these ratios, NLR has the highest predictive value for disease deterioration.