Sex differences in out-of-hospital cardiac arrest

Abstract Aims The impact of resuscitation care initiatives on sex-differences in out-of-hospital cardiac arrest (OHCA) survival remains unclear. We aim to examine sex-differences in characteristics and survival. Methods and results This Danish register-based study (2001–2020) included adult patients with a presumed cardiac cause of arrest. Temporal trends in survival were stratified by sex and subgroups: (i) bystander-witnessed status; (ii) bystander cardiopulmonary resuscitation (CPR); (iii) initial shockable heart rhythm; and age groups of <50, 50–75, and >75 years. To examine the association between sex and survival, we conducted adjusted logistic regression analyses. Among 50 066 OHCAs, women represented 34%. Women were older, had more chronic obstructive pulmonary disease, and lower prevalence of cardiovascular and cardiometabolic conditions than men. Women also had more OHCA at home (83.4 vs. 74.1%), fewer witnessed arrests (48.1 vs. 52.9%), half the probability of initial shockable heart rhythm (13.6 vs. 27.6%), and similar rates of receiving bystander-CPR. Survival rates improved over time for both sexes, but men had higher 30-day survival than women, even in subgroup and adjusted analyses [odds ratios (OR): 1.29; 95% confidence intervals (CI): 1.15–1.45, P < 0.001]. Sex-differences in survival were larger among those aged 50–75 years (in absolute and relative rates) and bystander witnessed arrests, while differences were smaller in those with initial shockable heart rhythms. Conclusion Despite increases in 30-day survival for both sexes, women consistently had lower survival rates than men. Sex-differences were larger among those aged 50–75 years or with bystander witnessed arrests, but smaller in the subset of patients with an initial shockable heart rhythm.