The neutrophil/lymphocyte ratio as a prognostic factor in COVID-19 patients: a case-control study

OBJECTIVE: SARS-CoV-2 (Se- vere Acute Respiratory Syndrome Coronavirus 2) has been identified in China as responsible for viral pneumonia, now called COVID-19 (Coro- navirus Disease 2019). Patients infected can de- velop common symptoms like cough and sore throat, and, in severe cases, acute respiratory syndrome and even death. To optimize the avail- able resources, it is necessary to identify in ad- vance the subjects that will develop a more se- rious illness, therefore requiring intensive care. The neutrophil / lymphocyte ratio (NLR) param- eter, resulting from the blood count, could be a significant marker for the diagnosis and man- agement of risk stratification. PATIENTS AND METHODS: A retrospective, single-center case-control observational study was conducted. The differential cell count of leu- kocytes, the NLR and the clinical course of pa- tients hospitalized in intensive care with COVID-19 were analyzed, comparing them with other pa- tients (COVID-19 and non-COVID-19) and healthy individuals selected among workers of the Teach- ing Hospital Policlinico Umberto I in Rome. RESULTS: 370 patients (145 cases and 225 controls) were included in the case-control study, 211 males (57%) and 159 females (43%). The average age of the population was 63 years (SD 16.35). In the group of cases, out of 145 pa- tients, 57 deaths and 88 survivors were record- ed, with a lethality rate of 39.3%. The group of cases has an NLR of 7.83 (SD = 8.07), a much higher value than the control group where an NLR of 2.58 was recorded (SD = 1.93) (p <0.001). The Neutrophils / Lymphocytes ratio may prove to be a diagnostic factor for COVID-19, an NLR> 3.68 revealed an OR 10.84 (95% CI = 6.47 - 18.13) (p <0.005). CONCLUSIONS: The value of NLR considered together with the age variable allows a risk strat- ification and allows the development of diagnos- tic and treatment protocols for patients affect- ed by COVID-19. A high neutrophil to lymphocyte ratio suggests worse survival. Risk stratification and management help alleviate the shortage of medical resources and reduce the mortality of critically ill patients.