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. 2025 Apr 28;5(3):oeaf047.
doi: 10.1093/ehjopen/oeaf047. eCollection 2025 May.

Sex differences in out-of-hospital cardiac arrest

Nertila Zylyftari  1   2   3 , Mads Wissenberg  1 , Filip Gnesin  2 , Amalie Lykkemark Møller  4   5 , Elisabeth Helen Anna Mills  6   7 , Sidsel G Møller  8 , Britta Jensen  9 , Kristian Bundgaard Ringgren  10 , Hanno L Tan  11   12 , Fredrik Folke  1   8   13 , Gunnar Gislason  1   13   14 , Christian Torp- Pedersen  2   4 , Christina Ji-Young Lee  2   15
Affiliations

Sex differences in out-of-hospital cardiac arrest

Nertila Zylyftari et al. Eur Heart J Open. .

Abstract

Aims: The impact of resuscitation care initiatives on sex-differences in out-of-hospital cardiac arrest (OHCA) survival remains unclear. We aim to examine sex-differences in characteristics and survival.

Methods and results: This Danish register-based study (2001-2020) included adult patients with a presumed cardiac cause of arrest. Temporal trends in survival were stratified by sex and subgroups: (i) bystander-witnessed status; (ii) bystander cardiopulmonary resuscitation (CPR); (iii) initial shockable heart rhythm; and age groups of <50, 50-75, and >75 years. To examine the association between sex and survival, we conducted adjusted logistic regression analyses. Among 50 066 OHCAs, women represented 34%. Women were older, had more chronic obstructive pulmonary disease, and lower prevalence of cardiovascular and cardiometabolic conditions than men. Women also had more OHCA at home (83.4 vs. 74.1%), fewer witnessed arrests (48.1 vs. 52.9%), half the probability of initial shockable heart rhythm (13.6 vs. 27.6%), and similar rates of receiving bystander-CPR. Survival rates improved over time for both sexes, but men had higher 30-day survival than women, even in subgroup and adjusted analyses [odds ratios (OR): 1.29; 95% confidence intervals (CI): 1.15-1.45, P < 0.001]. Sex-differences in survival were larger among those aged 50-75 years (in absolute and relative rates) and bystander witnessed arrests, while differences were smaller in those with initial shockable heart rhythms.

Conclusion: Despite increases in 30-day survival for both sexes, women consistently had lower survival rates than men. Sex-differences were larger among those aged 50-75 years or with bystander witnessed arrests, but smaller in the subset of patients with an initial shockable heart rhythm.

Keywords: 30-day survival; ESCAPE-NET; Female sex; Out-of-hospital cardiac arrest (OHCA); PARQ-COST; Women.

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Conflict of interest statement

Conflict of interest: Dr Zylyftari received grants from European Union’s Horizon 2020 research and innovation programme under acronym ESCAPE-NET, COST Action PARQ supported by COST (European Cooperation in Science and Technology), and Helsefonden. Dr Møller received grants from Karen Elise Jensen Fonden, Helsefonden and was employed by Novo Nordisk A/S after the project commenced. Novo Nordisk A/S is not engaged in this study. Dr Tan reports receiving grants from European Union’s Horizon 2020 research and innovation programme under acronym ESCAPE- NET (grant agreement no 733381), and COST Action PARQ supported by COST (European Cooperation in Science and Technology, grant agreement no CA19137). Dr Folke is supported by an unrestricted clinical research grant from the Novo Nordisk Foundation. Drs Gislason and Torp-Pedersen reports receiving grant support and honoraria from Bayer and Novo Nordisk. The remaining authors have no disclosures to report.

Figures

Graphical Abstract
Graphical Abstract
Figure 1
Figure 1
The crude 30-day out-of-hospital cardiac arrest survival by sex in percentage and number of survivors per 100 000 inhabitants per year.
Figure 2
Figure 2
The crude 30-day out-of-hospital cardiac arrest survival according to sex and age categories (<50, 50–75, and >75 years old) shown in (A) percentages and (B) number of survivors per 100 000 inhabitants per year.
Figure 3
Figure 3
The crude 30-day survival rates of out-of-hospital cardiac arrest patients according to sex and (A) bystander-witnessed status, (B) cardiopulmonary resuscitation efforts from bystander, and (C) first recorded heart rhythm.
Figure 4
Figure 4
Association between sex and 30-day survival following out-of-hospital cardiac arrest in adjusted analyses. Odds ratio of 30-day survival by sex and in subgroups of out-of-hospital cardiac arrest population in men as compared to women (the reference group). EMS, Emergency Medical Services; OHCA, out-of-hospital cardiac arrest. R2 = 0523. The model with the main population (*) was adjusted for age, comorbidities (respiratory diseases, diabetes type 2, ischaemic heart disease, heart failure, and hypertension), medication (antidepressant and psychotropic drugs, and short therapy within 30 days to out-of-hospital cardiac arrest with antibiotics, QT-prolonging drugs), cardiac related factors (location of arrest, witnessed status, initial shockable heart rhythm, bystander defibrillation, bystander cardiopulmonary resuscitation, response time, and return of spontaneous circulation upon hospital arrival), and invasive procedure (PCI) on the day of out-of-hospital cardiac arrest. †Adjusted for age, comorbidities (respiratory diseases, diabetes type 2, ischaemic heart disease, heart failure, and hypertension), medication (antidepressant and psychotropic drugs, and short therapy within 30 days to out-of-hospital cardiac arrest with antibiotics, QT-prolonging drugs), cardiac related factors (location of arrest, defibrillation status, bystander cardiopulmonary resuscitation, response time, return of spontaneous circulation upon hospital arrival), and invasive procedure (PCI) on the day of out-of-hospital cardiac arrest. ¥Adjusted for age, comorbidities (respiratory diseases, diabetes type 2, ischaemic heart disease, heart failure, and hypertension), medication (antidepressant and psychotropic drugs, and short therapy within 30 days to out-of-hospital cardiac arrest with antibiotics, QT-prolonging drugs), cardiac-related factors (location of arrest, witnessed status, defibrillation status, bystander cardiopulmonary resuscitation, response time, and the return of spontaneous circulation upon hospital arrival), and invasive procedure (PCI) on the day of out-of-hospital cardiac arrest. §Adjusted for age, comorbidities (respiratory diseases, diabetes type 2, ischaemic heart disease, heart failure, and hypertension), medication (antidepressant and psychotropic drugs, and short therapy within 30 days to out-of-hospital cardiac arrest with antibiotics, QT-prolonging drugs), cardiac-related factors (location of arrest, return of spontaneous circulation upon hospital arrival), and invasive procedure (PCI) on the day of out-of-hospital cardiac arrest.
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