Recent trends in survival from out-of-hospital cardiac arrest in the United States

Abstract

Background: Despite intensive efforts over many years, the United States has made limited progress in improving rates of survival from out-of-hospital cardiac arrest. Recently, national organizations, such as the American Heart Association, have focused on promoting bystander cardiopulmonary resuscitation, use of automated external defibrillators, and other performance improvement efforts.

Methods and results: Using the Cardiac Arrest Registry to Enhance Survival (CARES), a prospective clinical registry, we identified 70 027 U.S. patients who experienced an out-of-hospital cardiac arrest between October 2005 and December 2012. Using multilevel Poisson regression, we examined temporal trends in risk-adjusted survival. After adjusting for patient and cardiac arrest characteristics, risk-adjusted rates of out-of-hospital cardiac arrest survival increased from 5.7% in the reference period of 2005 to 2006 to 7.2% in 2008 (adjusted risk ratio, 1.27; 95% confidence interval, 1.12-1.43; P<0.001). Survival improved more modestly to 8.3% in 2012 (adjusted risk ratio, 1.47; 95% confidence interval, 1.26-1.70; P<0.001). This improvement in survival occurred in both shockable and nonshockable arrest rhythms (P for interaction=0.22) and was also accompanied by better neurological outcomes among survivors (P for trend=0.01). Improved survival was attributable to both higher rates of prehospital survival, where risk-adjusted rates increased from 14.3% in 2005 to 2006 to 20.8% in 2012 (P for trend<0.001), and in-hospital survival (P for trend=0.015). Rates of bystander cardiopulmonary resuscitation and automated external defibrillator use modestly increased during the study period and partly accounted for prehospital survival trends.

Conclusions: Data drawn from a large subset of U.S communities suggest that rates of survival from out-of-hospital cardiac arrest have improved among sites participating in a performance improvement registry.

Keywords: cardiac arrest; survival; trends.

Figure 1

Definition of Study Cohort

Figure 2. Unadjusted Rates of Survival to Hospital Discharge by Calendar Year

Observed rates for survival to discharge are displayed for the overall cohort and separately for shockable (ventricular fibrillation [VF] and pulseless ventricular tachycardia [VT]) and non-shockable (asystole and pulseless electrical activity [PEA]) cardiac arrest rhythms.

Figure 3. Trends in Neurological Outcomes

Compared to a discharge CPC score of 1 (little to no neurological disability), there was a significant trend (P for trend of 0.01) for lower rates of neurological disability over time.