The role of the neutrophil/lymphocyte ratio as a biomarker predicting the severity of COVID-19 infection

At the end of 2019, several cases of pneumonia provoked by an unknown causative agent were identified in China. In March 2020, the World Health Organization announced a pandemic of a new strain of Coronavirus - SARS-CoV-2. The neutrophil/lymphocyte ratio (NLR) is a biomarker that has recently become an important diagnostic and prognostic indicator in many diseases. The study‘s objective was to look for a relationship between NLR and the outcome of Covid-19 infection. Retrospectively, we studied 288 patients (mean age 69.1 ± 12.5) treated in an intensive pulmonology unit over ten months since 01.08.2021. All patients had severe pneumonia caused by SARS-CoV-2 infection, proven by a polymerase chain reaction (PCR) test. Leukocytes, lymphocytes, neutrophils, and NLR were traced. Hundred and seventy-four (60.4%) of the patients died, and the rest were discharged with improvement. Concerning NLR, we found values of 9.52 in the group of the deceased and 7.87 in those discharged, respectively, at the beginning. In the end, this indicator increased in the group of deceased to 15.04, while we found a drop to 7.3 in those discharged. A statistically significant difference was found regarding the outcome of the disease and the change in the NLR values in dynamics (p = 0.005). NLR is a cheap and reliable biomarker that can predict the outcome of Covid-19 infection.