title: Potential impact of public access defibrillators on survival after out of hospital cardiopulmonary arrest: retrospective cohort study.
abstract: OBJECTIVE
  To estimate the potential impact of public access defibrillators on overall survival after out of hospital cardiac arrest.
  
  
  METHODS
  Retrospective cohort study using data from an electronic register. A statistical model was used to estimate the effect on survival of placing public access defibrillators at suitable or possibly suitable sites.
  
  
  METHODS
  Scottish Ambulance Service.
  
  
  METHODS
  Records of all out of hospital cardiac arrests due to heart disease in Scotland in 1991-8.
  
  
  METHODS
  Observed and predicted survival to discharge from hospital.
  
  
  RESULTS
  Of 15 189 arrests, 12 004 (79.0%) occurred in sites not suitable for the location of public access defibrillators, 453 (3.0%) in sites where they may be suitable, and 2732 (18.0%) in suitable sites. Defibrillation was given in 67.9% of arrests that occurred in possibly suitable sites for locating defibrillators and in 72.9% of arrests that occurred in suitable sites. Compared with an actual overall survival of 744 (5.0%), the predicted survival with public access defibrillators ranged from 942 (6.3%) to 959 (6.5%), depending on the assumptions made regarding defibrillator coverage.
  
  
  CONCLUSIONS
  The predicted increase in survival from targeted provision of public access defibrillators is less than the increase achievable through expansion of first responder defibrillation to non-ambulance personnel, such as police or firefighters, or of bystander cardiopulmonary resuscitation. Additional resources for wide scale coverage of public access defibrillators are probably not justified by the marginal improvement in survival.
authors.affiliation: Department of Medical Cardiology, University of Glasgow, G31 2ER, b Scottish Ambulance Service Headquarters, Edinburgh EH10 5UU.
authors.forename: Jill P
authors.initials: JP
authors.lastname: Pell
authors.forename: Jane M
authors.initials: JM
authors.lastname: Sirel
authors.forename: Andrew K
authors.initials: AK
authors.lastname: Marsden
authors.forename: Ian
authors.initials: I
authors.lastname: Ford
authors.forename: Nicola L
authors.initials: NL
authors.lastname: Walker
authors.forename: Stuart M
authors.initials: SM
authors.lastname: Cobbe
mesh_terms: D016887:Cardiopulmonary Resuscitation / Q000191:economics / Q000295:instrumentation*; D015331:Cohort Studies; D003362:Cost-Benefit Analysis; D004554:Electric Countershock / Q000191:economics / Q000295:instrumentation*; D004638:Emergency Treatment / Q000295:instrumentation*; D004864:Equipment and Supplies / Q000600:supply & distribution; D006297:Health Services Accessibility; D006323:Heart Arrest / Q000191:economics / Q000401:mortality / Q000628:therapy*; D006801:Humans; D011379:Prognosis; D012189:Retrospective Studies; D012606:Scotland / Q000453:epidemiology; D016019:Survival Analysis