Association between bystander type and successful bystander-delivered shocks in urban Tokyo, Japan

Objective: To evaluate the association between bystander type and successful bystanderdelivered shocks among out-of-hospital cardiac arrest (OHCA) patients with an initial shockable rhythm. Methods: This single-center, retrospective observational study included non-traumatic adult OHCA patients with witnessed and an initial shockable rhythm who were transported to our hospital between April 2013 and June 2024. The term "successful bystander-delivered shocks" was defined as use of an automated external defibrillator by a bystander before emergency medical services arrival. Bystanders were categorized as family members, lay bystanders, on-duty staff, or healthcare professionals. On-duty staff were defined as persons working at the scene at the time of OHCA, and lay bystanders as non-staff passers-by . The primary outcome was successful bystander-delivered shocks . Multivariable logistic regression analyses were performed. Results: 285 patients were included. Median age was 59 [49-69] years, 254 (89.1%) were male, and 184 (64.6%) received bystander-initiated cardiopulmonary resuscitation. The bystander was a family member in 54 cases, a lay bystander in 79 cases, on-duty staff in 131 cases, and a healthcare professional in 21 cases. Successful bystander-delivered shocks differed markedly by bystander type: 3.7% among family members, 36.7% among lay bystanders, 59.5% among on-duty staff, and 76.2% among healthcare professionals. In multivariable logistic regression, the adjusted odds ratios for successful bystander-delivered shocks by bystander type were on-duty staff, 2.29 [1.26-4.17]; healthcare professionals, 6.26 [1.96-19.9]; and family members, 0.08 [0.02-0.36], compared with lay bystanders. Conclusion: OHCA patients for whom the rescuing bystander was on-duty staff or a healthcare professional were significantly more likely to receive successful bystanderdelivered automated external defibrillator shocks than those rescued by lay bystanders.