Development of a point-of-care mortality risk score for hospitalized COVID-19 patients

ABSTRACT

Rationale While several COVID-19-specific mortality risk scores exist, they lack the ease of use given their dependence on online calculators and algorithms. Objectives: The objectives of this study were (1) to design, validate, and calibrate a simple, easy-to-use mortality risk score in a hospitalized COVID-19 population. Methods: Multi-hospital health system in New York City. Patients (n=4840) with laboratory-confirmed SARS-CoV2 infection who were admitted between March 1 and April 28, 2020. Gray's K-sample test for the cumulative incidence of a competing risk was used to assess and rank 48 different variables' associations with mortality. Candidate variables were added to the composite score using DeLong's test to evaluate their effect on predictive performance (AUC) of in-hospital mortality. Final AUCs for the new score, SOFA, qSOFA, and CURB-65 were assessed on an independent test set. Results: Of 48 variables investigated, 36 (75%) displayed significant (p<0.05 by Gray's test) associations with mortality. The variables selected for the final score were (1) oxygen support level, (2) troponin, (3) blood urea nitrogen, (4) lymphocyte percentage, (5) Glasgow Coma Score, and (6) age. The new score, COBALT, outperforms SOFA, qSOFA, and CURB-65 at predicting mortality in this COVID-19 population AUCs for initial, maximum, and mean COBALT scores were 0.81, 0.91, and 0.92, compared to 0.77, 0.87, and 0.87 for SOFA. Conclusions: The COBALT score provides a point-of-care tool to estimate mortality in hospitalized COVID-19 patients with superior performance to SOFA and other scores currently in widespread use.