Neutrophil Lymphocyte Ratio as a Marker of In-Hospital Deterioration in COVID-19: Observations From a Resource Constraint Setting

Introduction and Objectives: The study was conducted to assess the association of neutrophil lymphocyte ratio (NLR) in COVID-19 and to identify the cut-off value that predicts mortality, need of respiratory support and admission to high-dependency or intensive care. Methods: A retrospective observational study was conducted to collect demographic data, clinical variables, the neutrophil-lymphocyte ratio on-admission and the outcome of confirmed COVID-19 patients admitted to a tertiary care center in Sri Lanka. Results: There were 208 patients with a median age of 56 years (IQR 43-67) and 98 (47.1%) males. The median neutrophil count was 4.07 × 103/µL (IQR 2.97-6.79) and the median lymphocyte count was 1.74 × 103/µL (IQR 1.36-4.75). The calculated NLR ranged from 0.12 to 48.28 with a median value of 2.32 (IQR 1.37-4.76). A NLR value >3.6 predicted development of severe disease requiring respiratory support, transfer to a high-dependency or an intensive care unit and/or succumbing to the illness with a sensitivity 80% and specificity 80% (area under the curve 0.8, 95% CI 0.72-0.88, P < .0001). The adjusted odds ratio of NLR > 3.6 on predicting severe disease was 11.1, 95% CI 4.5- 27.0, P < .0001. Conclusions: A NLR > 3.6 is a useful variable to be included in risk prediction scores in Sri Lanka.