Survival and neurological outcome after bystander versus lay responder defibrillation in out-ofhospital cardiac arrest: A sub-study of the BOX trial

Background and aim: Bystander defibrillation is associated with increased survival with good neurological outcome after out -of -hospital cardiac arrest (OHCA). Dispatch of lay responders could increase defibrillation rates, however, survival with good neurological outcome in these remain unknown. The aim was to compare long-term survival with good neurological outcome in bystander versus lay responder defibrillated OHCAs. Methods: This is a sub -study of the BOX trial, which included OHCA patients from two Danish tertiary cardiac intensive care units from March 2017 to December 2021. The main outcome was defined as 3 -month survival with good neurological performance (Cerebral Performance Category of 1or 2, on a scale from 1 (good cerebral performance) to 5 (death or brain death)). For this study EMS witnessed OHCAs were excluded. Results: Of the 715 patients, a lay responder arrived before EMS in 125 cases (16%). In total, 81 patients were defibrillated by a lay responder (11%), 69 patients by a bystander (10%) and 565 patients by the EMS staff (79%). The 3 -month survival with good neurological outcome was 65% and 81% in the lay responder and bystander defibrillated groups, respectively (P = 0.03). Conclusion: In patients with OHCA, 3 -month survival with good neurological outcome was higher in bystander defibrillated patients compared with lay responder defibrillated patients.