Dynamic Profile of Prognostic Hematologic Indicators in Patient Under Intensive Care for COVID-19 Disease: A One-Year Study at a Tertiary Care Centre in South India

Introduction Viral pneumonia caused by severe acute respiratory syndrome coronavirus 2 (SARS COV-2) releases cytokines which result in neutrophils migration to the bloodstream and cytotoxic effect on lymphocytes. The ongoing pathology is reflected in the derangement of blood cells and the variations and calculations based on them that help in assessing the severity of the disease and prognosis. Aim This study aimed to compare the differences in the dynamic changes of the blood cells among survivors and non-survivors of COVID-19 disease so that cut-offs can be arrived at to aid triage at the intensive care unit (ICU) and to predict mortality.  Material and methods A one-year study was conducted on patients hospitalized in the ICU. The demography and laboratory values of neutrophils and lymphocytes in percentages and absolute values, and platelet count in numbers were retrieved for eight consecutive values. Neutrophil to lymphocyte ratio (NLR) and platelet to lymphocyte ratio (PLR) was calculated from absolute counts. Statistical analysis was done using the Chi-Square test and Mann-Whitney test and a P-value of <0.05 is considered significant. The comparison was done between survivors and non-survivors. Result Among the 3142 patients admitted for COVID-19 disease, 7.6% required ICU care of whom 65.5% survived and 35.5% succumbed to the illness. Survivors were younger and comparable between both sexes. Though both groups had an ascending trend of neutrophils, lymphocytes, NLR, and PLR, the baseline characteristics were significantly lower in those who survived on a day-to-day basis. Neutrophilia above 80%, NLR 7.96, PLR 200 predicted the need for admission in ICU. Neutrophilia of 87% and lymphopenia of 10% were associated with adverse outcomes (mortality). Mortality can be predicted when neutrophil rises above 93% or lymphocytes fall below 5.2%. An initial NLR of 7.96 and PLR of 160 as well as peak NLR of 12.29 and peak PLR 400 predict mortality. Conclusion Serial blood counts are essential for hospitalized patients with COVID-19 for early triaging, and to assess severity and prognosis. The NLR of 6.7 and PLR of 160 require intensive care. The dynamic increase of NLR and PLR show worsening of the disease process and NLR of 40.95 and PLR of 400 predict mortality.