Complete Blood Count (CBC) and CBC derived Ratios in Early Diagnosis of COVID-19: A Retrospective Single-centre Study

ABSTRACT

Introduction: Abnormalities in Complete Blood Count (CBC) are frequently observed in Coronavirus Disease-2019 (COVID-19) infection. So, CBC can serve as a simple tool for the early diagnosis of COVID-19. Aim(s) To evaluate the diagnostic ability of CBC test in COVID-19 infection. Material(s) and Method(s) In this retrospective observational study, data were collected from 102 adult non critical care patients who presented with acute fever between May 2020 and December 2020. Among 102 patients' data, 48 were found Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) positive ('cases') and 54 were RT- PCR negative ('controls'). Non parametric Mann-Whitney test was used to compare the differences in CBC. The p-value <0.05 was considered statistically significant. Receiver Operator Characteristic (ROC) analysis was used to evaluate the diagnostic accuracy of CBC tests in COVID-19. For this, RT-PCR was used as the 'gold standard' and CBC as the index test. Area Under Curve (AUC) was determined for each of the CBC tests. All statistical analysis were done using Medcalc software. Result(s) The mean age of cases was 48+/-14 years (62% males;38% females) and controls was 45+/-15 years (55% males;45% females). Median values for haemoglobin, haematocrit, Red Blood Cell (RBC) count and Red cell Distribution Width (RDW) were significantly higher (p-value <0.05) and total White Blood Cell (WBC) count, eosinophil differential count, absolute eosinophil count, lymphocyte count, absolute lymphocyte count, immature granulocyte count were significantly lower in COVID-19 patients as compared to controls. Significant differences were observed for eosinophil (differential% and absolute) count. Almost all the platelet parameters were lower in COVID-19 patients (except Neutrophil Lymphocyte Ratio);although the platelet count was only mildly reduced in the RT-PCR positive cases (133-475 X 103/muL;median-227.98 X 103/muL). Higher AUC values were observed with Eosinophil-differential %, Eosinophil-absolute count, Eosinophil Lymphocyte Ratio (ELR) and NLR. Conclusion(s) Eosinophil count and associated ratio (Eosinophil Lymphocyte Ratio) are diagnostically useful and can serve as biomarkers for COVID-19. Further larger studies are needed to unravel the underlying mechanism and their clinical utility. Copyright © 2022 Authors. All rights reserved.