Bystander and emergency medical service responses to and outcomes of out-of-hospital cardiac arrest among domestic and non-domestic visitors in Japan

This study aimed to compare characteristics of emergency medical service (EMS)-transported emergencies and outcomes of out-of-hospital cardiac arrest (OHCA) among domestic and non-domestic visitors in Japan. Utstein-style OHCA registry data from 2018 to 2023 were merged with relevant transport data to identify patient residency status (domestic or non-domestic visitors). EMS-transported emergencies involving non-domestic visitors were characterised by higher incidences during non-daytime hours, in Tokyo, and at public locations and higher proportions of severe emergency cases. Non-domestic visitor OHCAs were associated with shorter EMS response time intervals, younger age, and lower proportions of witness, presumed cardiac aetiology, bystander cardiopulmonary resuscitation, and worse outcomes. Neurologically favourable 1-month outcomes of bystander-witnessed OHCA were significantly worse in non-domestic visitors than in domestic visitors, regardless of witness status and aetiology: 8.2% in non-domestic visitors (312/3817) vs. 14.4% in domestic visitors (2880/20,020) (adjusted odds ratio [95% confidence interval], 0.61 [0.55-0.68]). Bystander-witnessed OHCA outcomes remained worse in non-domestic visitors, even after propensity score matching (9.1% vs. 14.2%, 0.65 [0.54-0.79]; estimated difference [95% confidence interval], 3.7 [2.5-4.9] %). Worse OHCA outcomes in non-domestic visitors were likely due to disturbed bystander responses to OHCA and other potential barriers between bystanders and non-domestic visitors.