Investigating the factors influencing survival after out-of-hospital cardiac arrest: sex-based differences in resuscitation and outcomes (2021)
The objective of the studies in this dissertation was to examine the effects of sex on out-of-hospital cardiac arrest (OHCA) interventions and outcomes, including survival to hospital discharge, one-year survival, and survival with favourable neurological function. Data were obtained from the British Columbia (BC) Cardiac Arrest Registry, Population Data BC, and a multi-centre clinical trial carried out in the USA and Canada. Analysis methods comprised logistic regression, survival analysis, and multilevel analysis. The first study was an analysis of a cohort of 7,398 adults with OHCA in BC and showed that in patients who did not achieve prehospital ROSC, males had 1.2-fold greater odds of being transported to hospital compared to females (95% CI 1.04, 1.37).The second study was a retrospective analysis of 8,115 OHCA cases in BC and revealed that females had greater adjusted odds of ROSC (OR 1.29, 95% CI 1.15 – 1.42, p 0.001), but not survival to hospital discharge (OR 1.14, 95% CI 0.96 – 1.35, p = 0.129). The third study was an analysis of linked data from various clinical databases in BC and revealed no significant difference in one-year survival by sex (HR males vs. females 1.14, 95% CI 0.72 – 1.81, p = 0.57). The fourth study was a retrospective analysis of data (N=22,416) from the Resuscitation Outcomes Consortium multi-center randomized controlled trial. The study identified initial shockable rhythm and hypothermia management as the strongest predictors of favourable neurological outcome. Further analysis showed that males derived significantly greater benefit from hypothermia management and initial shockable rhythms than females.The fifth study was based on 23,725 cases from the trial mentioned above. The cohort was stratified into four groups by age and sex: younger females (i.e. premenopausal), older females, younger males, and older males. The study found no difference in neurological outcome between younger males and younger females (OR 0.95, 95% CI 0.69 – 1.32, p = 0.75). The result suggests premenopausal females had no advantage with respect to good brain function.These findings highlight the independent effect of sex on short and long-term survival, and the interaction effect of age and sex on neurological outcome.
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