Higher rates but similar causes of young out-of-hospital cardiac arrest in rural Australian patients

Objective: To determine whether young rural Australians have higher rates or different underlying causes of out-of-hospital cardiac arrest (OHCA). Design: A case–control design identified patients experiencing an OHCA, then compared annual OHCA rates and underlying causes in rural versus metropolitan Victoria. OHCA causes were defined as either cardiac or non-cardiac, with specific aetiologies including coronary disease, cardiomyopathy, unascertained cause of arrest, drug toxicity, respiratory event, neurological event and other cardiac and non-cardiac. For OHCAs with confirmed cardiac aetiology, cardiovascular risk profiles were compared. Setting: A state-wide prospective OHCA registry (combining ambulance, hospital and forensic data) in the state of Victoria, Australia (population 6.5 million). Participants: Victorians aged 1–50 years old experienced an OHCA between April 2019 and April 2020. Main outcome measures: Rates and underlying causes of OHCA in young rural and metropolitan Victorians. Results: Rates of young OHCA were higher in rural areas (OHCA 22.5 per 100 000 rural residents vs. 13.4 per 100 000 metropolitan residents, standardised incidence ratio 168 (95% CI 101–235); confirmed cardiac cause of arrest 12.1 per 100 000 rural residents versus 7.5 per 100 000 metropolitan residents, standardised incidence ratio 161 (95% CI 71–251). The underlying causation of the OHCA and cardiovascular risk factor burden did not differ between rural and metropolitan areas. Conclusion: Higher rates of OHCA occur in young rural patients, with standardised incidence ratio of 168 compared to young metropolitan residents. Rural status did not influence causes of cardiac arrest or known cardiovascular risk factor burden in young patients experiencing OHCA.