Regional Variation in Out-of-Hospital Cardiac Arrest Survival in the United States
Background—Although previous studies have shown marked variation in out-of-hospital cardiac arrest survival across U.S. regions, factors underlying this survival variation remain incompletely explained.
Methods and Results—Using data from the Cardiac Arrest Registry to Enhance Survival, we identified 96,662 adult patients with out-of-hospital cardiac in 132 U.S. counties. We used hierarchical regression models to examine county-level variation in rates of survival and survival with functional recovery (defined as Cerebral Performance Category score of 1 or 2) and examined the contribution of demographics, cardiac arrest characteristics, bystander cardiopulmonary resuscitation (CPR), automated external defibrillator (AED) use, and county-level socio-demographic factors in survival variation across counties. A total of 9317 (9.6%) patients survived to discharge, and 7176 (7.4%) achieved functional recovery. At a county-level, there was marked variation in rates of survival to discharge (range: 3.4%-22.0%, median odds ratio [MOR] 1.40, 95% CI 1.32-1.46) and survival with functional recovery (range: 0.8%-21.0%, MOR 1.53, 95% CI 1.43-1.62). County-level rates of bystander CPR and AED use were positively correlated with both outcomes (P<0.0001 for all). Patient demographic and cardiac arrest characteristics explained 4.8% and 27.7% of the county-level variation in survival, respectively. Additional adjustment of bystander CPR and AED explained 41% of the survival variation, and this increased to 50.4% after adjustment of county-level socio-demographic factors. Similar findings were noted in analyses of survival with functional recovery.
Conclusions—Although out-of-hospital cardiac arrest survival varies significantly across U.S. counties, a substantial proportion of the variation is due to differences in bystander response across communities.
- Received June 24, 2015.
- Revision received February 15, 2016.
- Accepted April 4, 2016.