Association of socioeconomic status with 30-day survival following out-of-hospital cardiac arrest in Scotland, 2011-2020.

Background and aims: The aim of this study was to investigate the crude and adjusted association of socioeconomic status with 30-day survival after out-of-hospital cardiac arrest (OHCA) in Scotland and to assess whether the effect of this association differs by sex or age.

Methods: This is a population-based, retrospective cohort study, including non-traumatic, non-Emergency Medical Services witnessed patients with OHCA where resuscitation was attempted by the Scottish Ambulance Service, between 1 April 2011 and 1 March 2020. Socioeconomic status was defined using the Scottish Index of Multiple Deprivation (SIMD). The primary outcome was 30-day survival after OHCA. Crude and adjusted associations of SIMD quintile with 30-day survival after OHCA were estimated using logistic regression. Effect modification by age and sex was assessed by stratification.

Results: Crude analysis showed lower odds of 30-day survival in the most deprived quintile relative to least deprived [odds ratio (OR) 0.74, 95% confidence interval (CI) 0.63-0.88]. Adjustment for age, sex, and urban/rural residency decreased the relative odds of survival further (OR 0.56, 95% CI 0.47-0.67). The strongest association was observed in males <45 years old. Across quintiles of increasing deprivation, evidence of decreasing trends in the proportion of those presenting with shockable initial cardiac rhythm, those receiving bystander cardiopulmonary resuscitation, and 30-day survival after OHCA were found.

Conclusions: Socioeconomic status is associated with 30-day survival after OHCA in Scotland, favouring people living in the least deprived areas. This was not explained by confounding due to age, sex, or urban/rural residency. The strongest association was observed in males <45 years old.