28 Utstein Survival The Utstein template was developed by international resuscitation experts to promote uniform reporting guidelines for clinical variables and patient outcomes 2,3 . These guidelines define core data fields to ensure consistency in terminology and make recommendations on the data elements to be recorded for each OHCA event. Patients who have a bystander witnessed OHCA and present in a shockable rhythm are the most likely to survive their arrest, and are referred to as the “Utstein” subgroup. This subset of arrests is an important measure of system efficacy, allowing for comparison of patient outcomes between systems and time periods, despite the wide variation of cardiac arrest circumstances and patient characteristics. Figure 20 shows the National CARES Utstein Survival Report for 2017. This report stratifies arrests by witness status and presenting rhythm. In 2017, the survival to hospital discharge rate for the Utstein subgroup was 32.6%. Utstein bystander patients (arrest witnessed by a bystander, presented in a shockable rhythm, and received some bystander intervention [CPR and/or AED application]) had a survival rate of 36.5%. Figure 20. 2017 CARES Non-Traumatic Etiology Utstein Survival Report.