Sex difference in the association between type of bystander CPR and clinical outcomes in patients with out of hospital cardiac arrest

BACKGROUND: A recent study suggested that women with out-of-hospital cardiac arrest have a smaller survival benefit with bystander cardiopulmonary resuscitation than men. We evaluated whether this weaker association between bystander cardiopulmonary resuscitation and survival in women is related to dispatcher-assisted vs unassisted bystander cardiopulmonary resuscitation. METHODS: In a national registry in the Republic of Korea, we identified adult patients with out-of-hospital cardiac arrest during 2013–2018. The main exposure was type of bystander cardiopulmonary resuscitation (categorized as none, dispatcher-assisted, and unassisted). The primary outcome was favourable neurological survival. Multivariable logistic regression evaluated for an interaction between sex and type of bystander cardiopulmonary resuscitation. RESULTS: Of 93,245 patients with out-of-hospital cardiac arrest, there were 31,578 (33.9%) women and 61,667 (66.1%) men. Overall, both types of bystander cardiopulmonary resuscitation were associated with favourable neurological survival (unassisted: adjusted OR, 1.81 [95% CI: 1.66–1.98]; dispatcher-assisted: adjusted OR, 1.44 [95% CI: 1.33–1.56]). When unassisted cardiopulmonary resuscitation was administered, the association between bystander cardiopulmonary resuscitation and favourable neurological survival was similar between women and men: adjusted ORs of 1.59 (95% CI: 1.30–1.95) in women and 1.88 (95% CI: 1.71–2.08) in men; interaction p = 0.65). In contrast, when dispatcher-assisted cardiopulmonary resuscitation was administered, the association differed by sex: adjusted ORs of 1.08 (95% CI: 0.90–1.92) in women and 1.55 (95% CI: 1.42–1.69) in men; interaction p < 0.0002). CONCLUSIONS: Dispatcher-assisted cardiopulmonary resuscitation was associated with favourable neurological survival in men but not in women whereas unassisted bystander cardiopulmonary resuscitation was associated with favourable neurological survival in women and men.