Clinical paperMedical versus non medical etiology in out-of-hospital cardiac arrest-Changes in outcome in relation to the revised Utstein template

IntroductionThe Utstein-style recommendations for reporting etiology and outcome in out-of-hospital cardiac arrest (OHCA) from 2004 have recently been revised. Among other etiologies a medical category is now introduced, replacing the cardiac category from Utstein template 2004.AimThe aim of this study is to describe characteristics and temporal trends from reporting OHCA etiology according to the revised Utstein template 2014 in regards to patient characteristics and 30-day survival rates.MethodsThis registry study is based on consecutive OHCA cases reported from the Emergency medical services (EMS) to the Swedish Registry of Cardiopulmonary Resuscitation (SRCR) 1992-2014. Characteristics, including a presumed cardiac etiology in Utstein template 2004, were transcribed to a medical etiology in Utstein template 2014.ResultsOf a total of n = 70,846 cases, 92% were categorized as having a medical etiology and 8% as having a non-medical cause. Using the new classifications, the 30-day survival rate has significantly increased over a 20-year period from 4.7% to 11.0% in the medical group and from 3% to 9.9% in the non-medical group (p ≤ 0.001). Trauma was the most common cause in OHCA of a non-medical etiology (26%) with a 30-day survival rate of 3.4% whilst drowning and drug overdose had the highest survival rates (14% and 10% respectively).ConclusionBased on Utstein 2014 categories of etiology, overall survival after OHCA with a medical etiology has more than doubled in a 20-year period and tripled for non-medical cases. Patients with a medical etiology found in a shockable rhythm have the highest chance of survival. There is great variability in characteristics among non-medical cases.