Abstract Body: Background:
The prevalence of overdose-associated out-of-hospital cardiac arrest (OA-OHCA) has grown over the past decade. Naloxone became available over the counter (OTC) in 2023. We evaluated recent trends in OA-OHCA in New Haven, CT, hypothesizing that the proportion of OA-OHCA treated by emergency medical services (EMS) after naloxone was made available over the counter would decrease.

Methods:
We conducted a retrospective analysis of OHCA patients treated by EMS clinicians in New Haven, Connecticut between 2021 and 2024. Our primary outcome was the proportion of OA-OHCA, defined as EMS impression of OHCA caused by a presumed or known drug overdose. We compared the proportion of individuals with OA-OHCA in 2021 and 2022 (before naloxone was made OTC) to the proportion of individuals with OA-OHCA in 2024 (after naloxone was made OTC).

Results:
From 2021 to 2024, 1,448 individuals suffered an OHCA resuscitated by EMS. Of these, 128 (8.8%) individuals were thought to have an OA-OHCA by EMS impression. The median [interquartile range] age of OA-OHCA was 43.0 [24,62); 90 (70.3%) were male. Before naloxone was made available OTC, 69/642 (10.7%) of OHCA were associated with overdose. This decreased to 13/300 (4.3%) of OHCA since naloxone was made available OTC. There was a significant decrease in OA-OHCA since naloxone became available OTC in 2023 (p = 0.001).

Conclusion:
The proportion of OHCA associated with overdose was observed to decrease in the year since naloxone became available over the counter.