The Diagnostic and Predictive Roles of Neutrophil-Lymphocyte Ratio for Severity of Disease in COVID-19 Patients

Neutrophil-lymphocyte ratio (NLR), lymphocyte-monocyte ratio (LMR), and platelet-lymphocyte ratio (PLR) are inflammation markers in inflammatory, cardiovascular, and malignant diseases and are important to assess prognosis. The aim of the study is to show the correlation between the inflammation markers of NLR, LMR, and PLR identified in total blood count of patients with Coronavirus disease 2019 (COVID-19) with the disease severity.

A total of 409 patients attending hospital with clinical symptoms of COVID-19 and with positive quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) test were divided into two groups as 61 severe patients and 348 non-severe patients. The levels of inflammation markers NLR, LMR, PLR, and c-reactive protein (CRP) were assessed.

The mean age of 409 patients was 49.9 ± 18.3 years and 48.7% of all patients were female. In the severe patient group, NLR 8.94 ± 13.24, LMR 2.24 ± 1.46, and PLR 248 ± 254 were identified. NLR exhibited the largest area under the curve at 0.698, with the highest specificity (67%) and sensitivity (67.3%) among the other inflammation markers such as LMR and PLR. Consistent with the severity of disease in severe COVID-19 patients, NLR, PLR, CRP and other inflammation markers increase, while LMR is observed to reduce.

NLR and PLR, calculated with the simple, cheap, and easily accessible hemogram test requested for diagnosis and follow-up of COVID-19 disease, were correlated with the total score for radiological findings and duration of hospitalization, and we observed NLR and LMR may predict disease severity.