Aims A short awareness time interval (ATI, time from witnessing the arrest to calling for help) and bystander cardiopulmonary resuscitation (CPR) are important factors affecting neurological recovery after out-of-hospital cardiac arrest (OHCA). This study investigated the association of the location of OHCA with the length of ATI and bystander CPR.

Methods This population-based observational study used the nationwide Korea OHCA database and included all adults with layperson-witnessed OHCA with presumed cardiac aetiology between 2013 and 2017. The exposure was the location of OHCA (public places, private housing and nursing facilities). The primary outcome was short ATI, defined as <4 min from witnessing to calling for emergency medical service (EMS). The secondary outcome was the frequency of provision of bystander CPR. Multivariable logistic regression analysis was performed to evaluate the association of location of OHCA with study outcomes.

Results Of 30 373 eligible OHCAs, 66.6% occurred in private housing, 24.0% occurred in public places and 9.4% occurred in nursing facilities. In 67.3% of the cases, EMS was activated within 4 min of collapse, most frequently in public places (public places 77.0%, private housing 64.2% and nursing facilities 64.8%; p<0.01). The overall rate of bystander CPR was 65.5% with highest in nursing facilities (77.0%), followed by public places (70.1%) and private housing 62.3%; p<0.01). Compared with public places, the adjusted ORs (AORs) (95% CIs) for a short ATI were 0.58 (0.54 to 0.62) in private housing and 0.62 (0.56 to 0.69) in nursing facilities. The AORs (95% CIs) for bystander CPR were 0.75 (0.71 to 0.80) in private housing and 1.57 (1.41 to 1.75) in nursing facilities.

Conclusion OHCAs in private housing and nursing facilities were less likely to have immediate EMS activation after collapse than in public places. A public education is needed to increase the awareness of necessity of prompt EMS activation.