The interaction effect of bystander cardiopulmonary resuscitation (CPR) and dispatcher CPR on outcomes after out-of-hospital cardiac arrest.

This study aimed to evaluate the effects of bystander cardiopulmonary resuscitation (CPR) and dispatcher-assisted CPR (DA-CPR) on outcomes after out-of-hospital cardiac arrest (OHCA). We conducted a prospective observational study using the Korean Cardiac Arrest Research Consortium registry database and enrolled adults aged > 20 years who sustained OHCA. The study population comprised 13,864 patients from October 1, 2015, to June 30, 2021. All enrolled patients were transported to the emergency room and resuscitated by the emergency medical personnel. Patients with terminal illnesses, pregnancy, "do not resuscitate" cards, and insufficient recorded information were excluded. Good neurologic outcomes were noted in 6.5%, 9.9%, and 9.6% of patients in the "no bystander", "standard bystander", and "compression-only bystander" CPR groups, respectively, and differed significantly (p < 0.001). Survival to discharge differed significantly (p < 0.001) between groups at 10.8%, 13.1%, and 13.2%, respectively. In a multivariable model, the interaction between "compression-only" and DA-CPR showed a positive effect on good neurological outcomes and survival to discharge with an odds ratio of 1.93 (Confidence interval, CI 1.28-2.91, p = 0.002) and 1.74 (CI 1.24-2.44, p = 0.001), respectively. In conclusion, the interaction between compression-only CPR and DA-CPR is significantly associated with good neurological and survival outcomes after OHCA. Education for bystanders and dispatchers should adhere to the current guidelines to improve outcomes among OHCA victims.