Aim: To determine the efficacy of neutrophil/lymphocyte ratio (NLR) as a marker of the severity of COVID-19 pneumonia in the South-Asian population.

Methods: This was a prospective, cross-sectional, analytic study conducted at HDU/ICU of District Headquarter Hospital, Faisalabad, Pakistan, from May through July 2020. Sixty-three eligible patients, admitted to the HDU/ICU, were prospectively enrolled in the study. Their NLR, C-reactive protein, serum albumin, and serum fibrinogen were measured. Patients’ demographic characteristics, comorbidities, clinical manifestations of COVID-19 infection, medication use, and history of lung malignancy were retrieved from their medical history. Patients were categorized into either a general group (with mild COVID-19) or a heavy group (with moderate to severe COVID-19).

Results: There were significant differences between the two groups in diabetes prevalence, NLR, C-reactive protein, and serum albumin. NLR and C-reactive protein were positively correlated (P < 0.001, P = 0.04 respectively) whereas serum albumin was negatively correlated (P = 0.009) with severe COVID-19. NLR was found to be an independent risk factor for severe COVID-19 pneumonia in the heavy group (OR = 1.264, 95% CI: 1.046~1.526, P = 0.015). The calculated AUC using ROC for NLR was 0.831, with an optimal limit of 4.795, sensitivity of 0.83 and specificity of 0.75, which is highly suggestive of NLR being a marker for early detection of deteriorating severe COVID-19 infection.

Conclusion: NLR can be used as an early warning signal for deteriorating severe COVID-19 infection and can provide an objective basis for early identification and management of severe COVID-19 pneumonia.

Keywords: COVID-19; Severity marker; Neutrophil/lymphocyte ratio; NLR; C-reactive protein; Albumin.