The impact of bystander relation and medical training on out-of-hospital cardiac arrest outcomes.

AIM: In this study, we investigate the impact of bystander relation and medical training on survival to hospital discharge in out-of-hospital cardiac arrest (OHCA) patients receiving bystander cardiopulmonary resuscitation (CPR). METHODS: A retrospective analysis was performed on non-traumatic OHCA patients receiving bystander CPR and Emergency Medical Service (EMS) attempted resuscitation from 2015 through 2017. Adjusted logistic regression was used to assess the association between related versus unrelated and layperson versus medically trained bystander CPR providers and survival to hospital discharge. RESULTS: A total of 4464 OHCA were eligible for inclusion, of which 2385 (53.4%) received CPR from a relative, 468 (10.5%) from a work colleague or friend and 1611 (36.1%) from a stranger. Layperson's provided CPR in 3703 (83.0%) OHCA and medically trained professionals in 761 (17.0%). After adjustment for arrest characteristics, there was no difference in survival to hospital discharge between related versus unrelated CPR (adjusted odds ratio [AOR] 0.92, 95% confidence interval [CI]: 0.68-1.23, p = 0.555). However, bystander CPR by a medically trained provider rather than a layperson, was associated with an increase in the odds of survival by 47% (AOR 1.47, 95% CI: 1.09-2.00, p = 0.012) in the overall population and 73% (AOR 1.73, 95% CI: 1.21-2.49; p = 0.003) in patients with an initial shockable arrest. Adjusting for public access defibrillation significantly attenuated the effect of medically trained bystander CPR in initial shockable arrests (AOR 1.42, 95% CI: 0.97-2.07; p = 0.073). CONCLUSION: This study supports ongoing efforts to crowdsource a larger number of first responders with medical training to OHCA patients to assist with the provision of CPR and early defibrillation.