Predicting the Risk of Intensive Care Unit Admission in Patients With COVID-19 Presenting in the Emergency Room: Development and Evaluation of the Confusion, Respiratory Rate, Oxygen Saturation With or Without Concurrent Supplemental Oxygen, and Oxygen Supplementation Score

Background Existing risk evaluation tools underperform in predicting intensive care unit (ICU) admission for patients with coronavirus disease 2019 (COVID-19). This study aimed to develop and evaluate an accurate and calculator-free clinical tool for predicting ICU admission at emergency room (ER) presentation. Methods Data from patients with COVID-19 in a nationwide German cohort (March 2020-January 2023) were analyzed. Candidate predictors were selected based on literature and clinical expertise. A risk score, predicting ICU admission within seven days of ER presentation, was developed using elastic net logistic regression on a northern German cohort (derivation cohort), evaluated on a southern German cohort (evaluation cohort), and externally validated on a Colombian cohort. Performance was evaluated through discrimination, calibration, and clinical utility against existing tools. Results ICU admission rates within seven days were 30.8% (derivation cohort, n = 1295, median age 60, 38.1% female), 28.1% (evaluation cohort, n = 1123, median age 58, 36.9% female), and 30.3% (Colombian cohort, n = 780, median age 57, 38.8% female). The 11-point CROSS score, based on Confusion, Respiratory rate, Oxygen Saturation (with or without concurrent supplemental oxygen), and oxygen Supplementation, demonstrated good discrimination (area under the curve: 0.77 in the evaluation cohort; 0.69 in the Colombian cohort), good calibration, and superior clinical utility compared to existing tools. Mortality-predicting tools performed poorly in predicting ICU admission risk for patients with COVID-19. Conclusions The calculator-free CROSS score effectively predicts ICU admission for patients with COVID-19 in the ER. Further studies are needed to assess its generalizability in other settings. Mortality-predicting tools are not recommended for ICU admission prediction.