Sex-related differences in the presentation and outcome of out-of-hospital cardiopulmonary arrest: A multiyear, prospective, population-based study

Objective: To examine whether previously observed sex-related differences in coronary artery disease syndromes also apply to patients with out-of-hospital sudden cardiac arrest, a probable subset of patients with coronary artery disease who are easy to recognize and are treated in a standardized fashion. Design: Prospective, population-based study conducted over a 6-yr period. Setting: A large urban municipality (population, 1.1 million) served by a single emergency medical services system with centralized medical direction and standardized protocols. Patients: All patients with out-of-hospital, nontraumatic, primary cardiac arrest. Interventions: Standardized advanced cardiac life support protocols. Measurements and Main Results: During the 6 yrs of the study, 4147 consecutive patients were studied, 42% of whom were women (p < .001). Although women were significantly older than men (mean age, 68.7 ± 18 vs. 61.7 ± 17 yrs; p = .001), there were no significant differences for the percentages of witnessed and unwitnessed arrests, response intervals, and the length and type of treatment provided. Although men were more likely to have ventricular fibrillation/ventricular tachycardia on presentation (41% vs. 30%), women had more asystole (8.8% vs. 7%) and (organized) pulseless electrical activity than men (24% vs. 18%; p < .001). Nevertheless, more women were resuscitated (13.5% vs. 10.7%; p = .005), particularly women with non-ventricular fibrillation/ventricular tachycardia presentation (12.6% vs. 9.6%; p < .02). These differences were more pronounced when controlling for age (95% confidence interval, 1.44 [1.25-1.74]). Conclusions: In cases of out-of-hospital sudden cardiac arrest, women have significantly better resuscitation rates than men, especially when controlling for age, particularly among women with non-ventricular fibrillation/ventricular tachycardia presentations. Additional studies are required to validate these observations, not only for long-term survival and external validity, but also for other potential genetic factors and potential discrepancies with other studies.