Zive DM, et al. - Using the Resuscitation Outcomes Consortium (ROC)epidemiological registry (Epistry), researchers assessed patient, event, system, treatment, and outcome data from adult (>18 years) out-of-hospital cardiac arrest (OHCA) from 10 geographically diverse North American ROC sites over four 12-month epochs, from July 1, 2011 to June 30, 2015. They characterized the sample using descriptive statistics and assessed the association of study epoch and key covariates on survival using logistic regression. As per findings, improvement in survival from adult OHCA was evident in multiple large geographically-separate sites over the study period. Persistence of marked site differences in survival led them to suggest considering this variation for improving outcomes from OHCA across North America.