September 14, 2026European Heart Journal
Reduction in incidence and fatality of out-of-hospital cardiac arrest in females of the reproductive age
Key result
Reproductive-age females are linked to lower OHCA incidence and ~100% higher neurologically intact survival versus males.
- OR 2.00
- 95% CI 1.21-3.32
- n=26,940
Why the study?
The relative risk of incidence and fatality of out-of-hospital cardiac arrest by gender and oestrogen status was not well defined.
Does female sex (specifically during reproductive age) reduce the incidence and improve neurologically intact survival of out-of-hospital cardiac arrest compared to males?
Population
26,940 patients with out-of-hospital cardiac arrest including 11,179 females and 15,701 males
Comparison
Females by age groups 0-12, 13-49, and ≥50 years vs males
Design
Prospective population-based observational study
Follow-up
1 month
Authors
Discussion
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Implication
Reproductive-age female OHCA survival advantage should not change practice; leaves open estrogen cardioprotection hypothesis.
Key Points
- To evaluate the relative risk of out-of-hospital cardiac arrest incidence and fatality across sexes according to estimated oestrogen status.
- Prospective, population-based observational study evaluating 26,940 cardiac arrests (11,179 females and 15,701 males) from 1998 through 2007.
- Participants were categorized by age based on menarche and menopause: 0–12 years, 13–49 years (reproductive age), and ≥50 years.
- Primary outcomes included age-adjusted incidence relative risk (RR) and 1-month neurologically intact survival assessed via adjusted odds ratios (OR).
- Age-adjusted RR of cardiac arrest incidence in females compared to males was 0.72 (95% CI, 0.58–0.91) in ages 0–12, 0.39 (95% CI, 0.37–0.43) in ages 13–49, and 0.54 (95% CI, 0.52–0.55) in age ≥50.
- Females aged 13–49 years demonstrated significantly higher neurologically intact 1-month survival than males (adjusted OR, 2.00; 95% CI, 1.21–3.32).
- Neurological recovery advantages were not statistically significant in other age groups, with adjusted ORs of 0.82 (95% CI, 0.06–12.02) for ages 0–12 and 1.23 (95% CI, 0.98–1.54) for age ≥50.
Study Design
Type
Observational (n=26,940)
Structured PICO
Does female sex (specifically during reproductive age) reduce the incidence and improve neurologically intact survival of out-of-hospital cardiac arrest compared to males?
P
Population
26,940 patients with out-of-hospital cardiac arrest evaluated in a prospective, population-based observational study from 1998 through 2007.
E
Exposure
Female sex (stratified by reproductive age 13-49 years as a proxy for estrogen status)
C
Comparator
Male sex
O
Outcome
Incidence of OHCA and neurologically intact 1-month survivalhard clinical
Main Result
Odds Ratio: 2 (95% CI 1.21–3.32)
Females of reproductive age have a lower incidence and better neurologically intact survival after out-of-hospital cardiac arrest compared to males, suggesting a potential cardioprotective effect of endogenous estrogen.
Cite This Study
Kitamura et al. (2010) conducted an observational in Out-of-hospital cardiac arrest (OHCA) (n=26,940). Female sex (reproductive age 13-49 years) vs. Male sex was evaluated on Neurologically intact 1-month survival (OR 2.00, 95% CI 1.21-3.32). Females of reproductive age (13-49 years) had a lower incidence of OHCA and higher odds of neurologically intact 1-month survival compared with males (OR 2.00; 95% CI 1.21-3.32).