Functional Access to Public Defibrillators and Out‐of‐Hospital Cardiac Arrest Outcomes: A Population‐Based Geospatial Analysis in Korea

BACKGROUND: Although public access defibrillation programs have expanded, real-world bystander automated external defibrillator (AED) use remains limited. The concept of functional accessibility, the realistic ability of bystanders to retrieve and use an AED within a time window that affects survival, has not yet been systematically evaluated. This study aimed to evaluate the functional accessibility of publicly installed AEDs by integrating factors influencing their usability in out-of-hospital cardiac arrest events. METHODS: We conducted a population-based geospatial analysis of 39 563 out-of-hospital cardiac arrests in Gyeonggi-do, Korea (2021-2023). Each incident was matched to the nearest public AED using network-based walking routes. Functional accessibility was measured by walking time and distance, stratified by urbanization, time of day, and location of arrest. Multivariable logistic regression was used to assess the association of AED accessibility with bystander AED use and prehospital return of spontaneous circulation. RESULTS: The median walking time to the nearest AED was 1.9 minutes; only 25.4% of rural arrests were within 3 minutes. Among 17 285 resuscitation-attempted cases, bystander AED use occurred in 2.9%. Shorter walking time was a statistically significant predictor of AED use and prehospital return of spontaneous circulation. Nighttime and residential arrests showed markedly reduced AED use irrespective of proximity. Moreover, although home arrests accounted for 70% of cases, bystander defibrillation occurred in <2%. CONCLUSIONS: Functional accessibility determines both device use and survival outcomes. Policies should prioritize 24/7 external AED availability, integration of dispatcher-assisted public access defibrillation programs, and novel delivery systems, such as drones, to bridge the spatial and temporal gaps in access.