Study to determine the correlation of platelet-lymphocyte ratio in COVID 19 positive and negative severe acute respiratory infections cases

Abstract

Background: Severity of COVID 19 disease is related to the systemic inflammatory response triggered by the respiratory virus. Hematological alterations triggered by inflammation can be used as a marker to predict the severity of COVID 19 infection.Methods: 155 patients of severe acute respiratory infections (SARI) defined by World Health Organization (WHO) criteria of which 65 were COVID positive and 90 COVID negative were taken for the study. Demographic profile of the population and platelet count, lymphocyte count and platelet lymphocyte ratio was compared between COVID 19 positive and negative SARI cases using appropriate descriptive statistics. Correlation analysis done for the same parameters between severe and moderate COVID 19 SARI cases.Results: Median platelet count in COVID positive group (2.47 L) was lower than that of COVID negative group (2.65 L) and was not statistically significant between 2 groups. Median lymphocyte count in COVID positive group (651) was lower compared to the negative group (1250) and difference was statistically significant. PLR in COVID positive group was higher (353) than COVID negative group (198) and was statistically significant (p value 0.00). PLR was higher in severe COVID disease compare to moderate disease but difference was not statistically significant. No significant correlation was found in platelet count, lymphocyte count in moderate and severe COVID positive SARI cases.Conclusions: Lower lymphocyte counts was observed in SARI caused by COVID 19 infection than other causes of SARI. No significant correlation was found in platelet count between COVID positive and negative SARI cases. PLR was significantly higher in COVID positive SARI cases as compared to COVID negative SARI cases. Platelet lymphocyte ratio (PLR) was higher in severe COVID disease when compared to moderate disease but levels did not reach statistical significance.