Abstract 273: Implications of Expanding the Utstein Case Definition for Out of Hospital Cardiac Arrest

Abstract

Background: The Utstein population is defined by non-traumatic, bystander-witnessed out-of-hospital cardiac arrest (OHCA) presenting with ventricular fibrillation (VF). It is used to compare resuscitation performance across emergency medical services (EMS) systems. We hypothesized there being a system-specific survival correlation between the current Utstein and other VF populations inclusive of unwitnessed and EMS-witnessed VF OHCA that supports expanding performance metrics to this more comprehensive population that is more representative of the actual community burden of VF OHCA. Methods: We performed a cohort investigation of all non-traumatic, VF OHCA in the Cardiac Arrest Registry to Enhance Survival from 1/1/2013-12/31/2018 among EMS agencies that treated >=100 VF OHCA. We evaluated sample size and survival with the addition of the new VF populations. We used the Pearson coefficient to assess the correlation of agency-specific survival between the current Utstein population and unwitnessed and EMS-witnessed VF OHCA. Results: A total of 107 EMS agencies treated 38,836 VF arrests: 22,918 current Utstein, 11,297 unwitnessed VF, and 4621 EMS-witnessed VF OHCA. Overall, survival was 29.8% (11,567/38,836): 33.9% (7,774/22,918) among current Utstein, 17.2% (1942/11,297) among unwitnessed VF, and 40.1% (1851/4621) among EMS-witnessed VF. For agency-specific survival outcome, the Pearson correlation was 0.52 between current the Utstein population versus combined unwitnessed and EMS-witnessed groups. For survival with Cerebral Performance Category 1-2, the Pearson correlation was 0.61. Conclusion: Expanding the Utstein population to include unwitnessed and EMS-witnessed VF OHCA achieves a simpler, more inclusive case definition that minimizes variability in case determination and increases the number of survivors and eligible population by ~50%, while still achieving a distinguishing metric of system-specific performance.