Impact of Bystander Cardiopulmonary Resuscitation and Dispatcher Assistance on Survival After Out-of-Hospital Cardiac Arrest Among Adult Patients by Location of Arrest.

We investigated the impact of bystander-initiated cardiopulmonary resuscitation (CPR), dispatcher assistance (DA), and location of arrest on survival and outcomes after out-of-hospital cardiac arrest (OHCA).From a nationwide population-based registry of OHCA patients in Japan, we enrolled adult patients with bystander-witnessed OHCA of medical origin between 2013 and 2015. The primary outcome measure was a neurologically favorable outcome, defined by cerebral performance category 1 or 2. Multivariable logistic regression analysis was used to assess the effects of bystander CPR and DA by location of arrest. A total of 104,621 cases were included (15,984 bystander CPR without DA [15.3%], 40,087 bystander CPR with DA [38.3%], and 48,550 no bystander CPR [46.4%]). In public locations, both the bystander-CPR-with-DA group (22.9% [1,068/4,665]; adjusted odds ratio (AOR), 1.62; 95% confidence interval (CI), 1.43-1.85) and the bystander-CPR-without-DA group (25.8% [918/3,557]; AOR, 1.43; 95% CI, 1.24-1.65) had neurologically favorable outcomes compared with the no-bystander-CPR group (9.9% [610/6,133]). In residential locations, the AORs were 1.44 (95% CI, 1.22-1.70) in the bystander-CPR-without-DA group and 1.60 (95% CI, 1.45-1.77) in the bystander-CPR-with-DA group. However, in nursing homes, bystander CPR was not associated with improved outcomes of OHCA, regardless of the implementation of DA.Bystander CPR with or without DA had better outcomes after OHCA in residential and public locations but not in nursing homes.