AB2CO risk score for in-hospital mortality of COVID-19 patients admitted to intensive care units

Purpose To develop a mortality risk score for COVID-19 patients admitted to intensive care units (ICU), and to compare it with other existing scores. Materials and Methods It is a retrospective observational study, including consecutive adult patients with laboratory-confirmed COVID-19 admitted to ICUs of 18 hospitals from nine Brazilian cities, from 09/2021 to 07/2022. Potential predictors were selected based on the literature review. Generalized Additive Models were used to examine outcomes and predictors. LASSO regression was used to derive the mortality score. Results From 558 patients, median age was 69 years (IQR 58-78), 56.3% were men, 19.7% required mechanical ventilation (MV), and 44.8% died. The final model comprised six variables: age, pO2/FiO2, respiratory function (respiratory rate or if in MV), chronic obstructive pulmonary disease, and obesity. The AB2CO had an AUROC of 0.781 (95% CI 0.744 to 0.819), good overall performance (Brier score=0.191) and an excellent calibration (slope=1.063, intercept=0.015, p-value=0.834). The model was compared with other scores and displayed better discrimination ability than the majority of them. Conclusions The AB2CO score is a fast and easy tool to be used upon ICU admission.