Neutrophil Lymphocyte Ratio and Platelet Lymphocyte Ratio as a predictor of mortality in severe COVID 19 cases

Background: With the periodic recurrence of Covid-19 waves affecting millions, there was an urgent need to identify accessible biological markers that could predict disease severity and mortality early in the illness. Neutrophil-Lymphocyte Ratio (NLR) and Platelet-Lymphocyte Ratio (PLR) have been proposed as potential inflammatory indicators for this purpose. Methods: A retrospective cohort study was conducted on 224 Covid-19 patients (August–October 2020). Patients were categorized into 'mild' and 'moderate to severe' groups. Mann-Whitney U and Chi-square tests were used for continuous and categorical variables, respectively. Receiver Operating Characteristic (ROC) analysis determined cut-off values for NLR, PLR, and age, along with sensitivity, specificity, and likelihood ratios. Results: Age, hemoglobin, and NLR were significant predictors of disease severity, with NLR showing the strongest association. Cut-off value of NLR > 4.24 demonstrated high sensitivity (88.3%) and specificity (82.6%) for severe disease. Cut off value of PLR > 165.63 also showed good predictive value. An NLR > 6 indicated increased mortality risk. Among those with NLR > 10, mortality was notably higher in the severe group. Conclusion: NLR and PLR are valuable, low-cost prognostic markers for assessing Covid-19 severity and mortality risk, particularly in low-resource settings. Their use can aid early intervention and treatment decisions.