Introduction
Out-of-hospital cardiac arrest (OHCA) is a public health concern in Australia, with approximately 22,000 cases attended by paramedics every year [1,2]. Despite advances in emergency medicine and resuscitation technology, survival from OHCA remains very low [3]. The outcomes after OHCA are highly time-dependent; accordingly, early interventions are crucial [4]. The chain-of-survival strategy for OHCA treatment emphasises a system-of-care approach, in which bystander-initiated interventions (bystander cardiopulmonary resuscitation [CPR], bystander defibrillation) prior to paramedic arrival are pivotal to improving patient outcomes [3,5]. Despite the proven benefits and substantial efforts to improve the rate of bystander interventions, less than half of OHCA patients globally receive bystander CPR, and less than 2% receive bystander defibrillation [6,7].
Although the reported survival rate is consistently low, previous studies have found significant variations in survival outcomes across countries and regions [1,8,9]. Such variations reflect differences in regional circumstances, patient characteristics, and clinical practices [10]. As such, policies and practice protocols need to reflect upon regional characteristics. An understanding of region-specific patient characteristics, outcomes and determinants of outcomes is critical for informing strategies to improve survival from OHCA in the region.
This present study aimed to investigate patient characteristics and survival from OHCA in the state of Queensland, Australia, using data from a large prospective, state-wide, population-based database. Factors associated with survival were also investigated, with a focus on bystander interventions. Furthermore, the average number of patients needed to receive a bystander intervention to save one life (i.e. number needed to treat) was estimated.