Trends in overdose-related out-of-hospital cardiac arrest in Arizona

Aim: Opioid overdose mortality has increased in North America; however, recent regional trends in the proportion of treated overdose-related out-of-hospital cardiac arrest (OD-OHCA) compared to out-of-hospital cardiac arrest of presumed cardiac etiology (C-OHCA) are largely unknown. Our aim is to assess trends in the prevalence and outcomes of OD-OHCAs compared to C-OHCAs in Arizona. Methods: Statewide, observational study utilizing an Utstein-style database with EMS-first care reports linked with hospital records, and vital statistics data from 2010 to 2015. Results: There were 21,658 OHCAs during the study period. After excluding non-C-OHCAs, non-OD-OHCAs, and cases missing outcome data, 18,562 cases remained. Of these remaining cases, 17,591 (94.8%) were C-OHCAs and 971 (5.2%) were OD-OHCAs. There was a significant increase in the proportion of OD-OHCAs from 2010, 4.7% (95% CI: 3.9-5.5) to 2015, 6.6% (95% CI: 5.8-7.5). Mean age for OD-OHCAs was 38 years compared to 66 years for C-OHCAs, (p < 0.0001). Initial shockable rhythm was present in 7.1% of OD-OHCAs vs. 22.6% of C-OHCAs (p < 0.0001). Overall survival to discharge in the OD-OHCA group was 18.6% vs. 11.9% in C-OHCA (p < 0.0001). After risk adjustment, we found an a OR of 2.1 (95% CI: 1.8-2.6) for survival in OD-OHCA compared to C-OHCA. Conclusion: There has been a significant increase in the proportion of OD-OHCAs in Arizona between 2010-2015. OD-OHCA patients were younger, were less likely to present with a shockable rhythm, and more likely to survive than patients with C-OHCA. These data should be considered in prevention and treatment efforts.