Abstract
AIM: The purpose of this study was to stratify patients who achieved return of spontaneous circulation (ROSC) after out-of-hospital cardiac arrest (OHCA) with bystander procedures pre-emergency medical service (EMS) arrival and those who achieved ROSC with procedures post-EMS arrival, compare outcomes at 1-month, and identify factors associated with pre-EMS-arrival-ROSC. METHODS: A retrospective cohort analysis of OHCAs occurring at stations in the Tokyo metropolitan area between 2014 and 2018 was conducted. Subjects were stratified by ROSC phase (categorized as pre- and post-EMS arrival and non-ROSC). Survival at 1-month post-OHCA and the percentage of favourable neurological function in each ROSC phase were analysed. In addition, factors associated with Pre-EMS-arrival-ROSC were identified using multivariable logistic regression analysis. The time of occurrence of OHCA was classified into four-time categories as follows. Rush hour on morning [7:00-9:00], Rush hour on evening [17:00-21:00], Daytime [9:00-17:00], and Night or Early morning [21:00-7:00]. RESULTS: Among the 63,089 OHCA in the dataset, 702 were analysed. At 1-month after OHCA occurrence, Pre-EMS-arrival ROSC had higher survival rates than post-EMS-arrival ROSC (86.8% vs. 54.1%) and CPC1-2 rates (73.6% vs. 38.5%). Pre-EMS-arrival ROSC was associated (adjusted odds ratio [95% confidence interval]) with non-older-adult patients (1.59 [1.05-2.43]), witnessed OHCA (1.82 [1.03-3.31]), evening rush-hour (17:00-21:00; 2.08 [1.05-4.11]), conventional CPR (33.42 [7.82-868.44]), hands-only CPR (17.06 [4.30-436.48]), bystander defibrillation performed once (3.31 [1.59-6.99]). CONCLUSIONS: In an OHCA at a station in Tokyo, ROSC achieved with bystander treatment alone had a better outcome at 1-month compared to ROSC with EMS intervention.