AED applied, not recommending defibrillation – A validation study of the new variable AED in the Danish Cardiac Arrest Registry

This study aimed to design and implement a new variable, the automated external defibrillator (AED) variable, within the Danish Cardiac Arrest Registry. The introduction of the new variable aims to investigate and solve the challenges of reporting out-of-hospital cardiac arrests. This validation study examined all patients with out-of-hospital cardiac arrest from 2016 to 2019. Their medical records were reviewed to establish a variable for AED. All patients with an AED applied were included, and comparative analyses were carried out. The primary outcome was 30-day survival, and the secondary outcome was the return of spontaneous circulation (ROSC) at any time. A total of 1576 cases were included; of those, 747 cases had an AED applied and received a shock, and in 829 cases, an AED was applied without delivering a shock. Most defibrillated patients were witnessed by bystanders n = 541, (72%). They presented a higher number of ROSC (57%) and higher 30-day survival, (35,2%) compared to patients who were not defibrillated. Of this group, only 47% patients were witnessed; 18% survived more than 30 days, p