Neutrophil-lymphocyte ratio as a simple tool to predict requirement of admission to a critical care unit in patients with COVID-19

Introduction: Coronavirus disease 2019 (COVID-19) pandemic has overloaded the healthcare system beyond its functional capacity. Late referral to higher levels of care may be one of the factors associated with higher mortality. Therefore, we aimed to find simple demographic and laboratory parameters which predict the requirement of admission to a critical care unit. Materials and methods: A case-control study was undertaken in adult age population >18 years, admitted in a dedicated COVID hospital in South India. A total of 50 patients with severe disease (cases) were compared with 143 mild or asymptomatic cases (controls). Those demographic and laboratory parameters that were found to be significant on univariate analysis were used for multiple logistic regression analysis. Results: Univariate analysis of demographic and laboratory data showed higher age, male sex, presence of diabetes mellitus, higher values of C-reactive protein, ferritin, D-dimer, neutrophil-lymphocyte ratio (NLR), and lactate dehydrogenase to be significantly associated with cases. Multivariate logistic regression analysis of these significant variables showed NLR and ferritin to be the independent predictors of the requirement of admission to a critical care unit. The receiver operating characteristic curve showed an NLR value of 5.2 and a ferritin value of 462 µg/L that were able to predict the requirement of admission in critical care units. Conclusion: High ferritin and NLR were independent predictors of the requirement of admission in critical care units. NLR is a simple tool that can be used in resource-limited settings for triage and early referral to higher levels of care.