Validation of utstein-based score to predict return of spontaneous circulation (UB-ROSC) in patients with out-of-hospital cardiac arrest

Abstract Funding Acknowledgements None. Background and aims The Utstein Based-ROSC (UB-ROSC) score has been developed to predict ROSC in OHCA victims. Aim of the study was to validate the UB-ROSC score using two Utstein-based OHCA registries: the SWiss REgistry of Cardiac Arrest (SWISSRECA) and the Lombardia Cardiac Arrest Registry (Lombardia CARe), northern Italy. Methods Consecutive patients with OHCA of any etiology occurring between January 1st, 2019 and December 31st 2021 were included in a prospectively designed validation study. UB-ROSC score was computed for each patient and categorized in one of 3 subgroups:low, medium or high likelihood of ROSC according to the UB-ROSC cut-offs (≤-19; -18 to 12; ≥13). To assess the performance of the UB-ROSC score in this new cohort, we assessed both discrimination and calibration. The score was plotted against the survival to hospital admission. Results A total of 12,577 patients were included in the study. A sustained ROSC was obtained in 2,719 patients (22%). The UB-ROSC model resulted well calibrated and showed a good discrimination (AUC 0.71, 95% CI 0.70-0.72). In the low likelihood subgroup of UB-ROSC, only 9% of patients achieved ROSC, whereas the proportion raised to 36% for a score between -18 and 12 (OR 5.0, 95% CI 2.9-8.6, P<0.001) and to 85% for a score ≥ 13 (OR 49.4, 95%CI 14.3-170.6, P <0.001). Conclusions UB-ROSC score represents a reliable tool to predict ROSC probability in OHCA patients. Its application may help the medical decision-making process, providing a realistic stratification of the probability for ROSC.