External validation of the 4C Mortality Score and PRIEST COVID-19 Clinical Severity Score in patients hospitalized with COVID-19 pneumonia in Greece.

Background: Prognostic scores can be used to facilitate better management of patients suffering from life-threatening diseases, provided that they have been tested in the population of interest. Aim: To perform external validation of the 4C Mortality Score and PRIEST COVID-19 Clinical Severity Score. Study Design: Prospective observational Study. Methods: Patients hospitalized with COVID-19 pneumonia in a tertiary hospital in Greece were enrolled in the study. The prognostic scores were calculated based on hospital admission data and ROC curve analysis was performed. We assessed a composite outcome of either in-hospital death or need for invasive ventilation. Results: Both 4C and PRIEST scores showed good discriminative ability with an AUC value of 0.826 (CI 95%: 0.765-0.887) and 0.852 (CI 95%: 0.793-0.910) respectively. Based on the Youden Index the optimal cut-off for the 4C score was 11 (Sensitivity 75%, Specificity 75.5%) and 10 for the PRIEST score (Sensitivity 83% and Specificity 69.4%). Calibration was adequate for both scores, except for the low and very high risk groups in the PRIEST score. Conclusion: The 4C Mortality Score and PRIEST COVID-19 Clinical Severity Score can be used for early identification of patients with poor prognosis in a Greek population cohort hospitalized with COVID-19.