Sex-Based Differences in Clinical Outcomes for Non-Prescription Drug-Associated Out-of-Hospital Cardiac Arrest

Introduction Non-prescription drug toxicity contributes to a substantial proportion of out-of-hospital cardiac arrests (OHCAs). Among OHCAs overall, previous reports have shown lower survival among females. We examined sex-based differences in outcomes among non-prescription drug-associated OHCA (DA-OHCA). Methods In this population-based observational cohort study using data from the BC Cardiac Arrest Registry (2019-24), we included emergency medical services (EMS)-treated OHCAs that had evidence of recent non-prescription drug use. The primary outcome was favorable neurological outcome, and secondary outcomes included survival at hospital discharge, prehospital return of spontaneous circulation (ROSC), ROSC at emergency department (ED) arrival. We assessed the association between female sex (vs male) and outcomes using multivariable logistic regression models, adjusted for Utstein variables. Results Among 47,051 EMS-Assessed OHCA, there were 4,926 adult EMS-assessed DA-OHCA. We included 3,133 adult EMS-treated DA-OHCAs, of whom 864 (28%) were female and 2,269 (72%) were male, with a median age of 38 (interquartile range [IQR] 30-49) and 40 (IQR 32-52) years, respectively. Favourable neurological outcomes occurred in 108 (13%) females and 212 (9.6%) males. Female sex was not associated with favourable neurological outcome (adjusted odds ratio [aOR] 1.32, 95% CI 0.97, 1.79), prehospital ROSC (aOR 1.00, 95% CI 0.83, 1.19), or ROSC at ED arrival (aOR 1.01, 95% CI 0.84, 1.22), but was associated with an increased odds survival to hospital discharge (aOR 1.34; 95% CI 1.01, 1.77). Conclusions Among DA-OHCA, female sex was not independently associated with favourable neurological outcomes, but was associated with a higher odds of survival to hospital discharge.