The association of non-prescription drug use preceding out-of-hospital cardiac arrest and clinical outcomes.

ABSTRACT

BACKGROUND: Clinicians may make prognostication decisions for out-of-hospital cardiac arrest (OHCA) using historical details pertaining to non-prescription drug use. However, differences in outcomes between OHCAs with evidence of non-prescription drug use, compared to other OHCAs, have not been well described. METHODS: We included emergency medical service-treated OHCA in the British Columbia Cardiac Arrest Registry (January/2019-June/2023). We classified cases as "non-prescription drug-associated cardiac arrests" (DA-OHCA) if there was evidence of non-prescription drug use preceding the OHCA, including witness accounts of use within 24 hours or paraphernalia at the scene. We fit logistic regression models to investigate the association between DA-OHCA (vs. other cases) and favourable neurological outcome (Cerebral Performance Category [CPC] 1-2) and survival at hospital discharge, and return of spontaneous circulation (ROSC). RESULTS: Of 34,745 OHCA, 2,171 (12%) were classified as DA-OHCA. DA-OHCA tended to be younger, unwitnessed, occur during the evening or night, and present with a non-shockable rhythm, compared to other OHCA. DA-OHCA (221 [10%]) had a greater proportion (difference 1.8%; 95%CI 0.49-3.2) with favourable neurological outcomes compared to other OHCA (1,365 [8.4%]). Adjusted models did not identify an association of DA-OHCA with favourable neurological outcome (OR 1.08, 95%CI 0.87-1.33) or survival to hospital discharge (OR 1.13, 95%CI 0.93-1.38), but did demonstrate an association with ROSC (OR 1.13, 95%CI 1.004-1.27). CONCLUSION: In unadjusted models, DA-OHCA was associated with an improved odds of survival and favourable neurological outcomes at hospital discharge, compared to other OHCA. However, we did not detect these associations in adjusted analyses.