Dispelling the remoteness myth- a geospatial analysis of where out-of-hospital cardiac arrests are occurring in Western Australia.

Background: Rurality has been shown to have a strong effect on survival from out-of-hospital cardiac arrest (OHCA), with survival in rural areas approximately half that of metropolitan areas. Western Australia provides a unique landscape to understand the impact of rurality, with 2.6 million people spread across 2.5 million km. We conducted a scale geospatial analysis with respect to population density and proximity to services, to understand the impact of rurality on bystander interventions, prehospital management and survival of OHCA patients.

Methods: We conducted a retrospective cohort study with a geospatial analysis of ambulance-attended, medical OHCA cases from 2015 to 2022. We compared bystander interventions, distances to services, population density and survival outcomes, stratified by a four-scale regional (broad scale) categorisation of rurality, and proximity to town scale.

Results: There were a total of 6,763 cases within the study cohort (Major Cities- 5,186, Inner Regional- 605, Outer Regional-599 and Remote- 373). The majority of OHCAs occurred within towns, and within close proximity to people and health services. Bystander interventions were higher for more remote cases. Increased distance from town was associated with a 5 % decrease per kilometre in the odds of Return of Spontaneous Circulation (ROSC) on arrival at hospital (OR = 0.95 [95 % Confidence Interval 0.92-0.98]). Despite close proximity to ambulance services, ambulance response times were more prolonged with increasing remoteness.

Conclusions: OHCA cases within regions classified as Regional and Remote typically occurred within towns, and in close proximity to emergency services. However, ambulance response times within rural and remote towns were long relative to their proximity to ambulance stations. These findings provide a new perspective on the issue of remoteness for OHCA cases.