Abstract
BACKGROUND: Out-of-hospital cardiac arrest (OHCA) has a high mortality rate worldwide. A first responder (FR) and automated external defibrillator (AED) network was implemented to complement emergency medical services (EMS) in the Swiss canton of Fribourg. This study aims to assess geospatial disparities in FR deployment, AED usage and prehospital response efficiency relative to OHCA clusters. METHODS: This retrospective observational study analysed all OHCA cases recorded in the Swiss Registry of Cardiac Arrest between 2018 and 2022, which occurred in the canton of Fribourg. We used visual spatial mapping to illustrate clusters of OHCA survival and explore their relationship with FR presence and AED use, including outcome proportions in five predefined geographical zones. Multivariate exact logistic regression models were constructed to assess the impact of the five geographical zones in which OHCA occurred on survival to hospital discharge. RESULTS: Of 1127 OHCA included, 34 % had a FR on-site and an AED was used in 19 % of cases. All OHCA clusters corresponded to the most densely inhabited areas. Survival rates were highest in urban areas (8.5 %) but decreased to 3.6 % in sparsely populated zones. Cardiopulmonary resuscitation (CPR) performance and AED use by first responders or bystanders showed no statistically significant impact across geographic areas. Heatmaps of FR deployment showed a lower intensity in urban areas and a more even distribution across the territory. Despite a higher AED density in urban areas, usage remained low (12 %). By the end of 2022, 2050 FRs and 549 AEDs were registered in the canton, which remains below international recommendations. CONCLUSION: Geospatial disparities highlighted the need for optimized FR recruitment, improved AED distribution and refined EMS activation strategies to enhance OHCA survival rates. These findings provide actionable insights for targeted resource allocation of the existing system at the cantonal level.