Sex-Specific Outcome Following Targeted Blood Pressure, Oxygenation, and Fever Control After Out-of-Hospital Cardiac Arrest

Background: Previous studies show higher mortality for female patients with out-of-hospital cardiac arrest (OHCA) compared to males. The BOX (Blood Pressure and Oxygenation Targets in Post Resuscitation Care) trial investigated the effects of different mean arterial pressure (MAP) targets, oxygenation levels, and durations of fever control, finding no significant differences between groups. Objectives: The purpose of this study was to explore the association between sex and mortality rates by examining both the individual and possible interactive effects of the interventions in the BOX trial for both sexes. Methods: This two-center, randomized trial included adult comatose OHCA patients (age ≥18 years) of presumed cardiac cause. Participants were assigned to a blinded MAP target of 63 or 77 mm Hg, open-label arterial oxygen levels of 9–10 or 13–14 kPa, and fever prevention for 36 or 72 hours. The primary outcome was 1-year all-cause mortality. Results: Of 789 comatose OHCA patients, 152 (19%) were females. The median ages of females and males were similar, 64 (51-71) years and 64 (55-73) years, respectively. Comorbidities and characteristics of the cardiac arrest were comparable between sexes except for ischemic heart disease (females: 12%, males 24%). Mortality in females was 42% and 35% in males; HR: 1.27 (95% CI: 0.96-1.69). None of the targeted interventions had a statistically significant impact on mortality for either sex. No mortality difference between sexes was observed across the interventions. Conclusions: Among comatose patients following OHCA, no differences were observed between sexes in 1-year mortality or the efficacy of the blood pressure, oxygen, or temperature intervention.