Mortality in ICU COVID-19 Patients Is Associated with Neutrophil-to-Lymphocyte Ratio (NLR): Utility of NLR as a Promising Immunohematological Marker

Background. Achieving a suitable medical laboratory index is very important for the prediction of clinical outcome of COVID-19 patients hospitalized to the intensive care unit (ICU). The correlation between neutrophil-to-lymphocyte ratio (NLR) and unfavorable outcome of COVID-19 patients hospitalized to ICU was the aim of this study. Methods. We evaluated a cross-sectional study of 312 COVID-19 patients who were hospitalized to the ICU (confirmed by PCR and CT-Scan), in Babol city, Mazandaran province. WBC, RBC, lymphocyte, neutrophil, monocyte, platelet count, NLR, C-reactive protein (CRP), ESR, MCV, MHC, and other factors were evaluated. Results. Our findings indicated that all patients aged 56 to 69 years with COVID-19 had a significant difference ( $P<0.05$ ) in neu, lymph, PLT count, NLR, ESR, Hb, and CRP. Also, NLR was significantly ( $P<0.05$ ) correlated with the death or discharge of the ICU hospitalized patients. The cut-off of NLR was 7.02 and the mean of NLR was 11.3 ± 10.93 and 5.8 ± 7.45 in death and discharge COVID-19 patients hospitalized to ICU, respectively. ROC curve indicated that, for NLR, the area under curve was 0.76. Conclusions. Our findings showed that NLR can be utilized as a clinical laboratory predictive parameter for mortality of COVID-19 patients admitted to ICU.