Usefulness of CURB-65, pneumonia severity index and MuLBSTA in predicting COVID-19 mortality

The aim of our study is to evaluate the accuracy of CURB-65 and Pneumonia Severity Index (PSI), the most widely used scores for community acquired pneumonia, and MuLBSTA, a viral pneumonia score, in predicting 28-day mortality in Coronavirus Disease 2019 (COVID-19) pneumonia.We retrospectively collected clinical data of consecutive patients with laboratory-confirmed COVID-19 pneumonia admitted at Papa Giovanni XXIII Hospital from February 23^rd to March 14^th, 2020. We calculated at Emergency Department (ED) presentation CURB-65, PSI and MuLBSTA and we compared their performances in discriminating between survivors and non-survivors at 28 days. Among 431 hospitalized patients, the majority presented with hypoxic respiratory failure: median (interquartile range, IQR) PaO₂/FiO₂ ratio at admission was 228.6 (142.0-278.1). In the first 24 hours, 111 (27%) patients were administered low-flow oxygen cannula, 50 (12%) Venturi Mask, 95 (23%) non-rebreather mask, 106 (26%) non-invasive ventilation, 12 (3%) mechanical ventilation and 41 (9%) were not administered oxygen therapy. Mortality rate at 28-day was 35% (150/431). Between survivors and non-survivors, median (IQR) scores were, respectively, 1.0 (1.0-2.0) and 2.0 (2.0-3.0) for CURB-65 (p<0.001); 90.5 (76.0-105.5) and 115.0 (100.0-129.0) for PSI (p<0.001); 7.0 (5.0-10.0) and 11.0 (9.0-13.0) for MuLBSTA (p<0.001). Areas under the receiver operating characteristic curve (AUCs) for each score were, respectively, 0.725 (0.662-0.787), 0.776 (0.693-0.859) and 0.743 (0.680-0.806) (p>0,05). PSI and MuLBSTA did not show a better performance when compared to CURB-65. Although CURB-65, PSI and MuLBSTA scores are useful tools to discriminate between survivors and non-survivors in COVID-19 pneumonia, their diagnostic accuracy in discriminating 28-day mortality in COVID-19 pneumonia is moderate, as confirmed by AUCs <0.80, and there is a potential underestimation of disease severity in the low-risk classes. For this reason, they should not be recommended in ED to decide between inpatient and outpatient management in patients affected by COVID-19 pneumonia.