Relationship between socioeconomic status and incidence of out-of-hospital cardiac arrest is dependent on age.

BACKGROUND: The association between socioeconomic status (SES) and incidence of out-of-hospital cardiac arrest (OHCA) is not fully understood. The aim of this study was to see if area-level socioeconomic differences, measured in terms of area-level income and education, are associated with the incidence of OHCA, and if this relationship is dependent on age.
METHODS: We included OHCAs that occurred in Stockholm County between the 1st of January 2006 and the 31st of December 2017, the victims being confirmed residents (n=10 574). We linked the home address to a matching neighbourhood (base unit) via available socioeconomic and demographic information. Socioeconomic variables and incidence rates were assessed by using cross-sectional values at the end of each year. We used zero-inflated negative binomial regression to calculate incidence rate ratios (IRRs).
RESULTS: Among 1349 areas with complete SES information, 10 503 OHCAs occurred between 2006 and 2017. The IRR in the highest versus the lowest SES area was 0.61 (0.50-0.75) among persons in the 0-44 age group. Among patients in the 45-64 age group, the corresponding IRR was 0.55 (0.47-0.65). The highest SES areas versus the lowest showed an IRR of 0.59 (0.50-0.70) in the 65-74 age group. In the two highest age groups, no significant association was seen (75-84 age group: 0.93 (0.80-1.08); 85+ age group: 1.05 (0.84-1.23)). Similar crude patterns were seen among both men and women.
CONCLUSIONS: Areas characterised by high SES showed a significantly lower incidence of OHCA. This relationship was seen up to the age of 75, after which the relationship disappeared, suggesting a levelling effect. © Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.