Role of Neutrophil-Lymphocyte Ratio in Predicting Severity of COVID-19

Abstract

Background: Higher neutrophil-lymphocyte ratio (NLR) is considered as cardinal findings with prognostic potentials in identification of severe COVID-19 cases. However, whether baseline NLR could be a predictor of disease severity and outcome remained to be investigated. Hence, this study was conducted with an aim to evaluate the relation of NLR (on admission) with disease severity. Objective: The objective of the study was to estimate the neutrophil-lymphocyte ratio among COVID-19 patients and its role in predicting disease severity. Method: This cross-sectional study was conducted in Bangabandhu Sheikh Mujib Medical University (BSMMU) from July 2020 to June 2021. Ninety-four COVID-19 admitted patients were enrolled following inclusion & exclusion criteria. Informed consent was taken from the subjects. Ethical clearance was obtained from institutional review board (IRB) of BSMMU. Complete blood count for N-L ratio was done by standard procedure on admission by SYSMEX XN-2000 haematology analyser. Clinical and laboratory information were recorded with a semi-structured questionnaire. After collection of all the required data, analysis was done by SPSS 24.0. Results: Mean age of the patients was 56.59±12.25 years, wherein maximum patients were male (67%), non-smoker (80.9%), and retired/current service holder (51.1%). Maximum patients were hypertensive (61.7%) and diabetic (56.4%). Besides, maximum study patients (64.9%) were in severe category of COVID-19, followed by moderate (20.2%) and mild (14.9%) category according to National Guidelines on Clinical Management of COVID-19 criteria. Mean NLR was 5.40±4.35 (SD), wherein on admission NLR was significantly higher among severe COVID-19 patients compared to mild/moderate category (6.90±4.64 vs 2.61±1.53, p <0.05). 28-days hospital mortality was found to be significantly associated with NLR (p<0.05). Receiver operator curve analysis found highly significant cut-off value for NLR (3.42) with 75.4% sensitivity and 75.8% specificity in predicting severe COVID-19 patients (AUC= 0.841, p value <0.001). Multivariate logistic regression analysis found NLR as an independent predictor for severe COVID-19 (OR=4.68, 95% CI: 1.29-16.81, P=0.019). Pearson correlation analysis showed that NLR had significant positive correlation with CRP and D-dimer as p value <0.05. Conclusion: NLR can predict the disease severity and outcome of hospitalized COVID-19 patients. However, further larger study is recommended.