Inequalities in Income and Education are Associated with Survival Differences after Out-of-hospital Cardiac Arrest: A Nationwide Observational Study.

Background: Despite the acknowledged importance of socioeconomic factors as regards cardiovascular-disease onset, and survival, the relationship between individual-level socioeconomic factors and survival after out-of-hospital cardiac arrest (OHCA) is not fully established. Our aim was to investigate whether socioeconomic variables are associated with 30-day survival after OHCA. Methods: We linked data from the Swedish Registry for Cardiopulmonary Resuscitation with individual-level data on socioeconomic factors (i.e. educational level and disposable income) from Statistics Sweden. Confounding and mediating variables included demographic factors, comorbidity and Utstein resuscitation variables. Outcome was 30-day survival. Multiple modified Poisson regression was used for the main analyses. Results: A total of 31,373 OHCAs occurring in 2010-2017 were included. Crude 30-day survival rates by income quintiles were: Q1 (low) 414/6277 (6.6%), Q2=339/6276 (5.4%), Q3=423/6275 (6.7%), Q4=652/6273 (10.4%) and Q5 (high) 928/6272 (14.8%). In adjusted analysis, the chance of survival by income level followed a gradient-like increase, with a risk ratio (RR) of 1.86 (95% CI 1.65-2.09) in the highest-income quintile vs. the lowest. This association remained after adjusting for comorbidity, resuscitation factors and initial rhythm. A higher educational level was associated with improved 30-day survival, the RR associated with post-secondary education ≥ 4 years being 1.51 (95% CI 1.30-1.74). Survival disparities by income and educational level were observed in both men and women. Conclusions: In this nationwide observational study using individual-level socioeconomic data, higher income and higher educational level were associated with better 30-day survival following OHCA, in both sexes.