<qa>  What is the effect of treatment group assessed while adjusting for other important prognosticatorsThe effect of treatment group will be assessed while adjusting for other important prognosticators in out-of-hospital cardiac arrest including initial cardiac rhythm, time to emergency medical services EMS arrival, bystander cardiopulmonary resuscitation CPR, EMS-witnessed arrest, and age. In addition, as the region of the cardiac arrest may be an independent predictor of outcomes, this will be included in the final adjustment. The investigators prospectively collected data on patients that fit the study criteria in both regions between 2012 and 2015. Outcomes in this historical data will be compared between regions, as well as historical data from each region individually compared to the study period, in order to estimate the independent effect of region of treatment. 