title: Increased survival after EMS witnessed cardiac arrest. Observations from the Resuscitation Outcomes Consortium (ROC) Epistry-Cardiac arrest.
abstract: BACKGROUND
  Out of hospital cardiac arrest (OHCA) is common and lethal. It has been suggested that OHCA witnessed by EMS providers is a predictor of survival because advanced help is immediately available. We examined EMS witnessed OHCA from the Resuscitation Outcomes Consortium (ROC) to determine the effect of EMS witnessed vs. bystander witnessed and unwitnessed OHCA.
  
  
  METHODS
  Data were analyzed from a prospective, population-based cohort study in 10 U.S. and Canadian ROC sites. Individuals with non-traumatic OHCA treated 04/01/06-03/31/07 by EMS providers with defibrillation or chest compressions were included. Cases were grouped into EMS-witnessed, bystander witnessed, and unwitnessed and further stratified for bystander CPR. Multiple logistic regressions evaluated the odds ratio (OR) for survival to discharge relative to the EMS-witnessed group after adjusting for age, sex, public/private location of collapse, ROC site, and initial ECG rhythm. Of 9991 OHCA, 1022 (10.2%) of EMS-witnessed, 3369 (33.7%) bystander witnessed, and 5600 (56.1%) unwitnessed.
  
  
  RESULTS
  The most common initial rhythm in the EMS-witnessed group was PEA which was higher than in the bystander- and unwitnessed groups (p<0.001). The adjusted OR (95% CI) of survival compared to the EMS-witnessed group was 0.41, (0.36, 0.46) in bystander witnessed with bystander CPR, 0.37 (0.33, 0.43) in bystander witnessed without bystander CPR, 0.17 (0.14, 0.20) in unwitnessed with bystander CPR and 0.21 (0.18, 0.24) in unwitnessed cases without bystander CPR.
  
  
  CONCLUSIONS
  Immediate application of prehospital care for OHCA may improve survival. Efforts should be made to educate patients to access 9-1-1 for prodromal symptoms.
authors.affiliation: University of Pittsburgh, Department of Emergency Medicine, Suite 400A, Pittsburgh, PA 15261, USA. hostlerdp@upmc.edu
authors.forename: David
authors.initials: D
authors.lastname: Hostler
authors.forename: Elizabeth G
authors.initials: EG
authors.lastname: Thomas
authors.forename: Scott S
authors.initials: SS
authors.lastname: Emerson
authors.forename: James
authors.initials: J
authors.lastname: Christenson
authors.forename: Ian G
authors.initials: IG
authors.lastname: Stiell
authors.forename: Jon C
authors.initials: JC
authors.lastname: Rittenberger
authors.forename: Kyle R
authors.initials: KR
authors.lastname: Gorman
authors.forename: Blair L
authors.initials: BL
authors.lastname: Bigham
authors.forename: Clifton W
authors.initials: CW
authors.lastname: Callaway
authors.forename: Gary M
authors.initials: GM
authors.lastname: Vilke
authors.forename: Tammy
authors.initials: T
authors.lastname: Beaudoin
authors.forename: Sheldon
authors.initials: S
authors.lastname: Cheskes
authors.forename: Alan
authors.initials: A
authors.lastname: Craig
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Davis
authors.forename: Andrew
authors.initials: A
authors.lastname: Reed
authors.forename: Ahamed
authors.initials: A
authors.lastname: Idris
authors.forename: Graham
authors.initials: G
authors.lastname: Nichol
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002170:Canada; D016887:Cardiopulmonary Resuscitation / Q000379:methods* / Q000401:mortality*; D015331:Cohort Studies; D004630:Emergencies; D004632:Emergency Medical Services / Q000458:organization & administration*; D005260:Female; D005500:Follow-Up Studies; D006323:Heart Arrest / Q000401:mortality* / Q000628:therapy*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D011446:Prospective Studies; D018570:Risk Assessment; D016019:Survival Analysis; D013997:Time Factors; D016896:Treatment Outcome; D014481:United States; D055815:Young Adult
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