Sex differences in outcome after targeting mean arterial blood-pressures and oxygenation in comatose patients after out-of-hospital cardiac arrest

Abstract

Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Novo Nordisk Foundation Background Previous studies have found lower survival rate and neurological outcomes for female patients with out-of-hospital cardiac arrest (OHCA) compared to males. Recently, the effect of liberal or restrictive oxygenation and lower or higher mean arterial blood-pressures (MAP) on outcome in comatose OHCA patients were investigated; showing no differences between the target groups. Evidence concerning sex differences in outcome after appropriate oxygenation and different MAP levels in comatose OHCA patients is limited. Purpose The aim of this study was to investigate whether female sex was associated with higher rates of unfavourable outcome after treatment with oxygenation and MAP in comatose patients after OHCA related to outcome. Methods Adult comatose OHCA patients (age ≥18 years) of presumed cardiac cause were included in a dual-center, double-blind, randomized trial with a 2-by-2 factorial design. Patients were allocated by a 1:1:1:1 ratio into a MAP target of 63 mm Hg or 77 mm Hg and arterial oxygen concentration during mechanical ventilation of 9–10 kPa (restrictive) or 13–14 kPa (liberal). The primary outcome was a composite of all causes of death within a year or hospital discharge with a cerebral performance category (CPC) of 3 or 4. Results Of the 789 included comatose OHCA patients, 152 (19%) were women. Mean age of women and men were similar, 61±14 years and 63±13 years, respectively. Comorbidities and characteristics of the cardiac arrest were comparable between sexes except for ischemic heart disease, which was more frequent in men (12% women, 24% men) and pulseless electrical activity, which was more frequent in women (8% women, 4% men). CPC 3 or 4 occurred equally in women and men (both 3%). Women had a higher, but non-significant one-year all-cause mortality (women: 42%, men: 35%), Figure 1. In a univariate Cox regression model, the difference in all-cause mortality was not significant (HR: 1.25, CI: 0.95-1.63), but showed significance after adjustment for age (HR: 1.31, CI: 1.004-1.72). Conclusion Men and women in comatose after OHCA had similar unfavourable outcome when treated in the same manner with oxygenation and MAP.