title: Survival after application of automatic external defibrillators before arrival of the emergency medical system: evaluation in the resuscitation outcomes consortium population of 21 million.
abstract: OBJECTIVE
  The purpose of this study was to assess the effectiveness of contemporary automatic external defibrillator (AED) use.
  
  
  BACKGROUND
  In the PAD (Public Access Defibrillation) trial, survival was doubled by focused training of lay volunteers to use an AED in high-risk public settings.
  
  
  METHODS
  We performed a population-based cohort study of persons with nontraumatic out-of-hospital cardiac arrest before emergency medical system (EMS) arrival at Resuscitation Outcomes Consortium (ROC) sites between December 2005 and May 2007. Multiple logistic regression was used to assess the independent association between AED application and survival to hospital discharge.
  
  
  RESULTS
  Of 13,769 out-of-hospital cardiac arrests, 4,403 (32.0%) received bystander cardiopulmonary resuscitation but had no AED applied before EMS arrival, and 289 (2.1%) had an AED applied before EMS arrival. The AED was applied by health care workers (32%), lay volunteers (35%), police (26%), or unknown (7%). Overall survival to hospital discharge was 7%. Survival was 9% (382 of 4,403) with bystander cardiopulmonary resuscitation but no AED, 24% (69 of 289) with AED application, and 38% (64 of 170) with AED shock delivered. In multivariable analyses adjusting for: 1) age and sex; 2) bystander cardiopulmonary resuscitation performed; 3) location of arrest (public or private); 4) EMS response interval; 5) arrest witnessed; 6) initial shockable or not shockable rhythm; and 7) study site, AED application was associated with greater likelihood of survival (odds ratio: 1.75; 95% confidence interval: 1.23 to 2.50; p < 0.002). Extrapolating this greater survival from the ROC EMS population base (21 million) to the population of the U.S. and Canada (330 million), AED application by bystanders seems to save 474 lives/year.
  
  
  CONCLUSIONS
  Application of an AED in communities is associated with nearly a doubling of survival after out-of-hospital cardiac arrest. These results reinforce the importance of strategically expanding community-based AED programs.
authors.affiliation: Johns Hopkins University, Baltimore, Maryland 21287, USA. mlw5@jhmi.edu
authors.forename: Myron L
authors.initials: ML
authors.lastname: Weisfeldt
authors.forename: Colleen M
authors.initials: CM
authors.lastname: Sitlani
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Ornato
authors.forename: Thomas
authors.initials: T
authors.lastname: Rea
authors.forename: Tom P
authors.initials: TP
authors.lastname: Aufderheide
authors.forename: Daniel
authors.initials: D
authors.lastname: Davis
authors.forename: Jonathan
authors.initials: J
authors.lastname: Dreyer
authors.forename: Erik P
authors.initials: EP
authors.lastname: Hess
authors.forename: Jonathan
authors.initials: J
authors.lastname: Jui
authors.forename: Justin
authors.initials: J
authors.lastname: Maloney
authors.forename: George
authors.initials: G
authors.lastname: Sopko
authors.forename: Judy
authors.initials: J
authors.lastname: Powell
authors.forename: Graham
authors.initials: G
authors.lastname: Nichol
authors.forename: Laurie J
authors.initials: LJ
authors.lastname: Morrison
mesh_terms: D000368:Aged; D001331:Automation; D002170:Canada / Q000453:epidemiology; D016887:Cardiopulmonary Resuscitation / Q000295:instrumentation*; D047548:Defibrillators; D004554:Electric Countershock / Q000295:instrumentation*; D004632:Emergency Medical Services / Q000379:methods*; D004867:Equipment Design; D005260:Female; D006323:Heart Arrest / Q000401:mortality* / Q000628:therapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D011446:Prospective Studies; D015996:Survival Rate / Q000639:trends; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology
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