Trends in sex differences in out-of-hospital cardiac arrest: an equity analysis in 2 cohorts (2012–2024)

OBJECTIVE. To analyze temporal trends in sex differences in non-traumatic out-of-hospital cardiac arrest (OHCA) and to assess whether improvements in the chain of survival have benefited women and men equitably.
MATERIALS AND METHODS. We conducted a retrospective observational study of two 36-month cohorts (2012–2014 and 2021–2024) including adult patients ($ 18 years) with non-traumatic OHCA attended by an urban emergency medical service. Cases with attempted cardiopulmonary resuscitation were included, with recorded sex, age, initial shockable rhythm (ISR), return of spontaneous circulation (ROSC), in-hospital survival, and neurological status at discharge according to the Cerebral Performance Category (CPC) scale. Logistic regression models adjusted for age and ISR were used, incorporating sex×cohort interaction terms.
RESULTS. A total of 1,750 episodes were analyzed (cohort 1, 806; cohort 2, 944). In both periods, women were older and had a lower frequency of ISR, which was the main predictor of favorable outcomes, showing a strong association with ROSC (OR, 2.79; 95 % CI, 2.26–3.45) and favorable neurological recovery (OR, 6.39; 95 % CI, 4.91–8.31). Age was inversely associated with ROSC. After adjustment, female sex was independently associated with a higher probability of ROSC (adjusted OR, 1.47; 95 % CI, 1.15–1.87; P = .002), with no significant differences in survival or neurological outcome. No statistically significant sex×cohort interactions were observed.
CONCLUSIONS. Crude sex differences in OHCA are largely explained by age and ISR. Although female sex was associated with a higher probability of ROSC after adjustment, this advantage did not translate into better subsequent outcomes. No significant changes in the sex gap over time were observed. Monitoring equity indicators and further exploration of process-related variables in future studies are recommended.