Diagnostic Utility of Platelet-Lymphocyte Ratio (PLR)and Platelet Parameters in COVID 19 Disease

ABSTRACT

Introduction: COVID-19 is an infectious disease caused by novelcoronavirus and changes in haematological parameters are recorded.Among which platelet parameters play an indirect role in assessingthe coagulation status of the patients.Aims &Objectives: The aim of this study is to (1) compare theplatelet parameters and PLR among ICU and non-ICU COVID-19patients (2) evaluate the role of platelet parameters in assessing theseverity in COVID-19 patients.Materials &Methods: This was a prospective observational studyfrom June 2020 to December 2020 (during the first wave of pandemic). The clinical data of patients were recruited from hospitalmedical records to stratify the disease severity. Parameters such asAbsolute lymphocyte count (ALC), Platelet count (PLT), MeanPlatelet Volume (MPV), Platelet Distribution Width (PDW), D-dimer,Prothrombin Time (PT) and activated Partial Thromboplastin Time(aPTT) were included. Values of Erythrocyte Sedimentation Rate(ESR) and Interlukein-6 (IL6) were also included wherever available.Serial platelet count values were noted for ICU patients for assessingthe platelet trend. From ALC and PLT count, platelet to lymphocyteratio (PLR) was calculated using the formula PLR = ALC/PLT 9100. Non-parametric independent 't' test was used to obtain thedifference between the study variables. ROC analysis was done tofind the optimum cut-off value of PLR between the tested groups.Result: A total of 218 RT-PCR proven COVID-19 patients wereincluded. Of these 145 (66.5%) patients were treated in ICU and73(33.5%) patients were treated in wards (non-ICU group). 39%patients showed thrombocytopenia at the time of admission. PLR,ALC and PDW showed statistically significant difference betweenICU and non-ICU group. Table 1 depicts the results.Conclusions: Haematological parameters provide vital clues aboutdisease severity. The most significant of them observed in our studyare ALC, PLR, PDW, D-dimer and ESR. Low values of ALC and high values of PLR, PDW, D-dimer andESR were associated with severe COVID-19 disease requiringICU care. PLR, an easily derivable parameter at a cut-off of 210.27 wasuseful to differentiate severe COVID disease from mild/moderateCOVID disease with 79% specificity.