Regional incidence and outcome of out-of-hospital cardiac arrest associated with overdose.

BACKGROUND

The frequency of lethal overdose due to prescription and non-prescription drugs is increasing in North America. The aim of this study was to estimate overall and regional variation in incidence and outcomes of out-of-hospital cardiac arrest due to overdose across North America.

METHODS

We conducted a retrospective cohort study using case data for the period 2006-2010 from the Resuscitation Outcomes Consortium, a clinical research network with 10 regional clinical centers in United States and Canada. Cases of out-of-hospital cardiac arrest due to drug overdose were identified through review of data derived from prehospital clinical records. We calculated incidence of out-of-hospital cardiac arrest due to overdose per 100,000 person-years and proportion of the same among all out-of-hospital cardiac arrests. We analyzed the association between overdose cardiac arrest etiology and resuscitation outcomes.

RESULTS

Included were 56,272 cases, of which 1351 were due to overdose. Regional incidence of out-of-hospital cardiac arrest due to overdose varied between 0.5 and 2.7 per 100,000 person years (p<0.001), and proportion of the same among all treated out-of-hospital cardiac arrests ranged from 0.8% to 4.0%. Overdose cases were younger, less likely to be witnessed, and less likely to present with a shockable rhythm. Compared to non-overdose, overdose was directly associated with return of spontaneous circulation (OR: 1.55; 95% CI: 1.35-1.78) and survival (OR: 2.14; 95% CI: 1.72-2.65).

CONCLUSIONS

Overdose made up 2.4% of all out-of-hospital cardiac arrest, although incidence varied up to 5-fold across regions. Overdose cases were more likely to survive than non-overdose cases.