Evaluation of lymphocyte count, T-cell subsets and neutrophil-to-lymphocyte ratio as early predictors for severity and outcome of COVID-19 disease–a report from a highly complex hospital in Brazil

INTRODUCTION: Lymphopenia is a laboratory marker of poor prognosis and severity of disease in the SARS-CoV-2 infection. This study aims to describe the immune profile of a Brazilian population. METHODS: A total of 121 consecutive patients with severe acute respiratory syndrome (SARS) were analyzed between April and June 2020. Routine peripheral blood counts and multiparametric flow cytometry were performed on admission to assess lymphocytes and subsets (CD3, CD4, CD8). Demographic, clinical and laboratory data were collected from hospital sources. RESULTS: The total of 116 patients included 63 (54.3%) males; 76 (62.8%) COVID-19 patients were divided, based on clinical characteristics and mechanical ventilation (MV) use, into moderate (n = 41; no MV) and severe (n = 35; MV) groups. The control group (n = 40) was comprised of patients with SARS of different etiologies. All patients had lymphopenia, with overall lymphocyte counts and their subsets considerably lower in severe patients, when compared to the moderate and controls. Patients with a high neutrophil-to-lymphocyte ratio (> 15.2) and T-cell lymphopenia (CD3 < 593 cells/µL, CD4 < 326 cells/µL, CD8 < 121 cells/µL) had a higher risk of being intubated and progressing to death. A total of 39 patients (95.1%) in the moderate group and 54.3% (n = 19) in the severe group were discharged; 28 patients died. CONCLUSION: Laboratory assessment of the neutrophil/lymphocyte ratio and T-cell subsets may be predictive of mortality and may be useful for stratifying COVID-19 patients.