Comparative Assessment of WBC Scattergram, Histogram and Platelet Indices in COVID-19 and Non COVID-19 Patients: A Cross-sectional Study

Abstract

Introduction: Coronavirus Disease 2019 (COVID-19) is an extremely transmissible infectious disease. Detection of coronavirus by Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) requires expert skills and moreover, it is not widely available in all the laboratories. Aim: To evaluate Red Blood Cell (RBC), platelet histogram and White Blood Cell (WBC) scattergram graphic patterns and interpretation of corresponding parameters along with peripheral smear in 500 COVID-19 RT-PCR positive study cases (COVID-19) and to compare them with normal study controls (non COVID-19). Materials and Methods: This was a laboratory-based observational study, conducted at a fully accredited National Accreditation Board for testing and calibration Laboratories’s (NABL) Central Diagnostic Research Laboratory, RL Jalapa Hospital Tamaka, Kolar, Karnataka, India from September 2020 to April 2021. RBC, platelet histogram, WBC scattergram graphic patterns with corresponding parameters were noted in RT-PCR COVID-19 positive patients and compared with controls using (Automated Haematology Analyser XN11500). Cases were further subcategorised into moderate and severe categories. For statistical analysis, Chi-square test or Fisher’s exact test, Independent t test was used for assessing qualitative and quantitative data respectively. Mean and standard deviation were depicted in box plots. Receiver Operating Characteristic (ROC) curve was used for predicting severity. A p-value <0.05 was considered statistically significant. Results: Among 500 subjects, males were 359 and females 141 with the mean age 50.5 years. Present study showed a characteristic finding of “sandglass” effect in WBC scattergram which is described as discontinuous cluster of plasmacytoid lymphocytes. RBC histogram and parameters did not show any significant changes. In severe COVID-19 cases among WBC parameters most common finding was neutrophilia. Platelet Lymphocyte Ratio (PLR), Platelet Monocyte Ratio (PMR), Platelet Neutrophil Ratio (PNR) were statistically significant in severe COVID-19 cases (p-value <0.001) corresponding ROC curve for WBC and platelet showed WBC count and PLR as the significant parameter in severe COVID-19 positive cases. Conclusion: Current study reported a specific and unique sandglass effect in WBC scattergram in severe COVID-19 subjects which can help the physicians for predicting the severity of disease and to prevent further progression of disease.