Retrospective observational cohort study of out-of-hospital cardiac arrest outcomes in Tasmania 2010-2014.

Time to defibrillation for witnessed arrests, other than paramedic witnessed arrest was associated with better overall survival rates than unwitnessed OHCA. Further factors such as the event being of cardiac aetiology, bystander cardio-pulmonary resuscitation performed, initial presenting cardiac rhythm of ventricular fibrillation or ventricular tachycardia and decreasing age were all associated with increased probability of survival.