Roles of CRP and Neutrophil-to-Lymphocyte Ratio in the Prediction of Readmission of COVID-19 Patients Discharged From the ED.

Background: Patient admissions beyond the capacity of emergency departments (EDs) have been reported since the coronavirus disease (COVID-19) pandemic. Thus, laboratory parameters to predict the readmission of patients discharged from the ED are needed. For this purpose, we investigated whether C-reactive protein (CRP) level and neutrophil-to-lymphocyte ratio (NLR) could predict the readmission of patients with COVID-19. Methods: Patients aged >18 years who visited the ED in October 2020 and had positive polymerase chain reaction test results were evaluated. Among these patients, those who were not hospitalized and were discharged from the ED on the same day were included in the study. The patients' readmission status within 14 days after discharge, age, sex, complaint on admission, comorbidity, systolic blood pressure, diastolic blood pressure, fever, pulse, oxygen saturation level, CRP level, blood urea nitrogen level, creatinine level, neutrophil count, lymphocyte count, and NLR were recorded. Data were compared between the groups. Results: Of the 779 patients who were included in the study, 359 (46.1%) were male. The median age was 41 years (range, 31-53 years). Among these patients, those who were not hospitalized and were discharged from the ED on logistic regression analysis, age, CRP level, NLR, loss of smell and taste, and hypertension had odds ratios of 2.494, 2.207, 1.803, 0.341, and 1.879, respectively. Conclusions: The strongest independent predictor of readmission within 14 days after same-day ED discharge was age > 50 years. In addition, CRP level and NLR were the laboratory parameters identified as independent predictors of ED readmission.