Where you live matters: socioeconomic disparities in out-of-hospital cardiac arrest incidence and survival in Western Australia – A population-based cohort study

Fig. 1. Sample selection flow-chart. aExclusions apply from 15-years of age, as ABS generates data for SES from 15 years of age. bThere are no arrests for <15 years at an aged-care facility or correctional facility. cSocioeconomic status [SES] derived from patient’s residential address at time of arrest based on the IRSD at a state-based SA1 level. dDefinition of a non-medical arrest.51

Fig. 2. Age-specific incidence of OHCA by SES quintiles, for the 10-year period between 2015 and 2024. (a) All OHCA cases (n = 23,957). (b) Resuscitation-attempted OHCA of medical aetiology (n = 8007). Note the difference in y-axis range between (a) and (b). “Medical OHCA” refers to resuscitation-attempted OHCA of medical aetiology (n = 8007). Age-specific incidence rates were calculated per 5-year age-group (years), using the ABS-defined WA population by IRSD quintile (2016 and 2021 census years) as the exposure population and presented per 100,000 adult population per year.47, 48 Q1 and Q5 denote the lowest (greatest disadvantage, low SES) and highest (least disadvantaged, high SES) SES quintiles, respectively, based on the SEIFA Index of Relative Socio-Economic Disadvantage [IRSD].32 Inset: Age-adjusted incidence rate ratios (IRRs) by SES (reference Q1) derived from negative binomial regression, adjusted for age and log of person-years. Statistical significance was set at p < 0.05.

Fig. 3. Effect of socioeconomic status on survival for resuscitation-attempted OHCA of medical aetiology (n = 8007). SES: Socioeconomic status; OHCA: Out-of-hospital cardiac arrest; ROSC: Return of Spontaneous Circulation on arrival to hospital; OR: Odds Ratio; 95%CI: 95% Confidence Interval. aSES quintiles were derived from the SEIFA Index of Relative Socio-Economic Disadvantage [IRSD] at an SA1 level for Western Australia.32 bAdjusted: SES (Quintile 1#); Sex (Female#); Age (years); OCHA Location (Private#); Initial Rhythm (Non-Shockable#); Witnessed OCHA (Unwitnessed#); Bystander CPR (No#); Year of OCHA (years); EMS Time to Respond (minutes). Covariate details are in supplementary material S2a – Model 3. # Denotes categorical variable reference group. cIndicates the reference group. *Note: all SES OR significant at p < 0.05.