This study, conducted by the Resuscitation Outcomes Consortium (ROC), aimed to evaluate regional variations in the incidence and outcome of out-of-hospital cardiac arrest (OHCA) in North America. The study included 10 sites with a total catchment population of 21.4 million, covering a period from May 1, 2006, to April 30, 2007. The primary outcomes assessed were incidence rate, mortality rate, case fatality rate, and survival to discharge for patients assessed by emergency medical services (EMS) and treated by EMS or with an initial rhythm of ventricular fibrillation. Key findings included: - The total number of OHCA cases was 20,520. - 61% of patients were male. - 58.0% of cases received resuscitation attempts. - 4.6% of patients were discharged alive. - The incidence of EMS-treated OHCA ranged from 40.3 to 86.7 per 100,000 population, with a median of 52.1. - The mortality rate ranged from 36.9 to 78.0 per 100,000 population, with a median of 47.0. - The case fatality rate ranged from 83.6% to 94.1%, with a median of 90.8%. - The survival to discharge ranged from 3.0% to 16.2%, with a median of 8.5%. The study observed significant regional differences in OHCA incidence and outcome, with p-values for differences across sites being < 0.001. These variations could be attributed to differences in the completeness of case ascertainment and local approaches to emergency response and post-resuscitation care. The findings highlight the need for further investigation to understand and address these regional disparities to improve public health outcomes.This study, conducted by the Resuscitation Outcomes Consortium (ROC), aimed to evaluate regional variations in the incidence and outcome of out-of-hospital cardiac arrest (OHCA) in North America. The study included 10 sites with a total catchment population of 21.4 million, covering a period from May 1, 2006, to April 30, 2007. The primary outcomes assessed were incidence rate, mortality rate, case fatality rate, and survival to discharge for patients assessed by emergency medical services (EMS) and treated by EMS or with an initial rhythm of ventricular fibrillation. Key findings included: - The total number of OHCA cases was 20,520. - 61% of patients were male. - 58.0% of cases received resuscitation attempts. - 4.6% of patients were discharged alive. - The incidence of EMS-treated OHCA ranged from 40.3 to 86.7 per 100,000 population, with a median of 52.1. - The mortality rate ranged from 36.9 to 78.0 per 100,000 population, with a median of 47.0. - The case fatality rate ranged from 83.6% to 94.1%, with a median of 90.8%. - The survival to discharge ranged from 3.0% to 16.2%, with a median of 8.5%. The study observed significant regional differences in OHCA incidence and outcome, with p-values for differences across sites being < 0.001. These variations could be attributed to differences in the completeness of case ascertainment and local approaches to emergency response and post-resuscitation care. The findings highlight the need for further investigation to understand and address these regional disparities to improve public health outcomes.