Survival after out-of-hospital cardiac arrest in relation to sex: A nationwide registry-based study

Aim

Crude survival has increased following an out-of-hospital cardiac arrest (OHCA). We aimed to study sex-related differences in patient characteristics and survival during a 10-year study period.

Methods

Patients ≥12 years old with OHCA of a presumed cardiac cause, and in whom resuscitation was attempted, were identified through the Danish Cardiac Arrest Registry 2001–2010. A total of 19,372 patients were included.

Results

One-third were female, with a median age of 75 years (IQR 65–83). Compared to females, males were five years younger; and less likely to have severe comorbidities, e.g., chronic obstructive pulmonary disease (12.8% vs. 16.5%); but more likely to have arrest outside of the home (29.4% vs. 18.7%), receive bystander CPR (32.9% vs. 25.9%), and have a shockable rhythm (32.6% vs. 17.2%), all p < 0.001. Thirty-day crude survival increased in males (3.0% in 2001 to 12.9% in 2010); and in females (4.8% in 2001 to 6.7% in 2010), p < 0.001.Multivariable logistic regression analyses adjusted for patient characteristics including comorbidities, showed no survival difference between sexes in patients with a non-shockable rhythm (OR 1.00; CI 0.72–1.40), while female sex was positively associated with survival in patients with a shockable rhythm (OR 1.31; CI 1.07–1.59). Analyses were rhythm-stratified due to interaction between sex and heart rhythm; there was no interaction between sex and calendar-year.

Conclusions

Temporal increase in crude survival was more marked in males due to poorer prognostic characteristics in females with a lower proportion of shockable rhythm. In an adjusted model, female sex was positively associated with survival in patients with a shockable rhythm.