Neutrophil-Lymphocyte Ratio as a Predictor of the Risk of Death in Severe Cases of COVID-19

Background: Identifying clinical characteristics and risk factors, comorbid conditions, and complications arising from SARS-CoV-2 infection is important to predict the progression to more severe forms of the disease among hospitalized individuals to enable timely intervention and to prevent fatal outcomes. The aim of the study is to assess the possible role of the neutrophil/lymphocyte ratio (NLR) as a biomarker of the risk of death in patients with comorbidities hospitalized with COVID-19 in a tertiary hospital in southern Brazil. Methods: This is a prospective cohort study on patients with SARS-CoV-2 infection admitted to a hospital in the metropolitan region of Porto Alegre from September 2020 to March 2022. Results: The sample consisted of 185 patients with associated comorbidities, namely, hypertension, diabetes mellitus, obesity, cardiovascular, pulmonary, and renal diseases, hospitalized with COVID-19. Of these, 78 died and 107 were discharged alive. The mean age was 66.5 years for the group that died and 60.1 years for the group discharged. Statistical analysis revealed that a difference greater than or equal to 1.55 in the NLR, from hospitalization to the 5th day, was associated with a relative risk of death greater than 2. Conclusions: Measuring a simple inflammatory marker such as NLR may improve the risk stratification of comorbid patients with COVID-19 and can be considered a useful biomarker.