Interhospital transfer in low-volume and high-volume emergency departments and survival outcomes after out-of-hospital cardiac arrest: A nationwide observational study and propensity score-matched analysis

Introduction: Post-resuscitation care of out-of-hospital cardiac arrest (OHCA) patients often involves inter-hospital transfer (IHT). We aimed to determine the association between IHT and outcomes of OHCA. Methods: This cross-sectional study used data from the nationwide emergency medical services (EMS)-based OHCA registry in Korea. All cases of adult patients with OHCA with a presumed cardiac aetiology and a sustained return of spontaneous circulation (ROSC) at hospitals between 2015 and 2016 were analysed. The primary outcome was a good neurological recovery at discharge, defined as cerebral performance in categories 1 or 2. We compared the primary outcome between a non-IHT group and an IHT group, using a propensity score-matching analysis. All analyses were performed separately by mean annual volume of patients with OHCA initially visiting high-volume emergency departments (HVEDs; >100 OCHA patients) and low-volume emergency departments (LVEDs; <= 100 OHCA patients). Results: Of 54,779 OHCA patients, 11,632 were included. Of 4477 patients who visited LVEDs initially, 1360 (30%) patients were transferred. Of 7155 patients who visited HVEDs initially, 604 (8%) patients were transferred. In the propensity score-matching analysis, the IHT group was more likely to have good neurological recovery than was the non-IHT group [ adjusted odds ratio (OR): 1.34; 95% confidence interval (CI): 1.07-1.67] in LVED visitors, but there was no significant difference of good neurological recovery between the non-IHT group and the IHT group (adjusted OR: 0.84; 95% CI: 0.63-1.13) in HVED visitors. Conclusion: IHT should be considered when treating OHCA patients in LVEDs.