Underlying reasons for sex difference in survival following out-of-hospital cardiac arrest: a mediation analysis.

AIMS: Previous studies have indicated a poorer survival among women following out-of-hospital cardiac arrest (OHCA), but the mechanisms explaining this difference remain largely uncertain.This study aimed to assess the survival after OHCA among women and men and explore the role of potential mediators, such as resuscitation characteristics, prior comorbidity, and socioeconomic factors. METHODS AND RESULTS: This was a population-based cohort study including emergency medical service-treated OHCA reported to the Swedish Registry for Cardiopulmonary Resuscitation in 2010-2020, linked to nationwide Swedish healthcare registries. The relative risks (RR) of 30-day survival were compared among women and men, and a mediation analysis was performed to investigate the importance of potential mediators. Total of 43 226 OHCAs were included, of which 14 249 (33.0%) were women. Women were older and had a lower proportion of shockable initial rhythm. The crude 30-day survival among women was 6.2% compared to 10.7% for men [RR 0.58, 95% confidence interval (CI) = 0.54-0.62]. Stepwise adjustment for shockable initial rhythm attenuated the association to RR 0.85 (95% CI = 0.79-0.91). Further adjustments for age and resuscitation factors attenuated the survival difference to null (RR 0.98; 95% CI = 0.92-1.05). Mediation analysis showed that shockable initial rhythm explained ∼50% of the negative association of female sex on survival. Older age and lower disposable income were the second and third most important variables, respectively. CONCLUSION: Women have a lower crude 30-day survival following OHCA compared to men. The poor prognosis is largely explained by a lower proportion of shockable initial rhythm, older age at presentation, and lower income.

Pulse pressure is not an independent predictor of incident atrial fibrillation in 60-year-old men and women.

AIM: To evaluate if pulse pressure (PP) is a risk predictor for atrial fibrillation (AF) in a longitudinal study of 60-year-old men and women from Stockholm (n = 4,232), free from AF at baseline, with primary end-point incident AF. METHODS: AF diagnoses were obtained from the national hospital discharge register. The estimated risk of AF associated with increasing PP values was calculated according to PP values above median (>52.5 mmHg) and according to 1-SD increase (14 mmHg) in PP, using a crude and an adjusted Cox proportional hazard regression model. RESULTS: During a mean follow-up of 13.6 years, 286 incident AF cases were recorded. The number of AF cases increased significantly with increasing PP quartile in men but not in women. PP values above median were associated with increased AF risk (crude HR 1.63, 95% CI 1.28-2.06; p < 0.001), but risk estimates were attenuated after adjustment for common AF risk factors. When PP was entered in the Cox regression model as a continuous variable, the risk of AF did not change by 1-SD PP increase (adjusted HR 1.04, 95% CI 0.91-1.20; p = 0.560). CONCLUSIONS: PP seems not to be associated with incident AF in a Swedish population of 60-year-old men and women.