title: The dispatcher assisted resuscitation trial: indirect benefits of emergency research.
abstract: OBJECTIVE
  Conduct of emergency research under waiver of consent produces special challenges. Moreover, the act of performing research may have unintended effects, potentially beneficial or detrimental. The Dispatcher-Assisted Randomized Trial (DART) was designed to compare 2 types of dispatcher cardiopulmonary (CPR) instruction, but not intended to affect the proportion of arrest victims that received bystander CPR. We sought to determine whether odds of receiving bystander CPR were higher during DART than during the periods before and after.
  
  
  METHODS
  We conducted an observational cohort study of 8626 adults who suffered non-traumatic out-of-hospital cardiac arrest prior to emergency medical services (EMS) arrival in greater King County, Washington, between January 1, 1999, and December 31, 2011. Bystander CPR status was assessed through review of dispatch recordings and EMS reports to classify any bystander CPR (any B-CPR), and further categorized as bystander CPR with or without dispatcher assistance (DA-CPR and B-CPR, no DA). We used multivariable logistic regression to evaluate odds of B-CPR before, during, and after DART.
  
  
  RESULTS
  The proportions receiving any B-CPR were 52% before DART (1817/3468), 59% during DART (2093/3527), and 54% after DART (885/1631). Compared to the period before DART, odds of receiving any B-CPR were higher during DART (OR=1.35, 95% CI=1.23-1.49), but no different after (OR=1.10, 0.98-1.24). Compared to the before period, odds of DA-CPR were higher during DART (OR=1.79, 1.59-2.02) but no different after (OR=0.94, 0.80-1.10).
  
  
  CONCLUSIONS
  Odds of bystander CPR were higher during the trial, an increase related to higher likelihood of DA-CPR. The finding suggests a possible indirect community-wide benefit due to the interventional trial.
authors.affiliation: Department of Epidemiology, University of Washington, Seattle, WA, USA; Department of Medicine, University of Washington, Seattle, WA, USA; Hospital & Specialty Medicine Service, VA Puget Sound Health Care System, Mail Stop S-111-MED, 1660 S Columbian Way, Seattle, WA 98108, US. Electronic address: lwander@u.washington.edu.
authors.forename: P L
authors.initials: PL
authors.lastname: Wander
authors.affiliation: Public Health-Seattle and King County, Emergency Medical Services Division, Seattle, WA, USA.
authors.forename: C E
authors.initials: CE
authors.lastname: Fahrenbruch
authors.affiliation: Department of Medicine, University of Washington, Seattle, WA, USA; Public Health-Seattle and King County, Emergency Medical Services Division, Seattle, WA, USA.
authors.forename: T D
authors.initials: TD
authors.lastname: Rea
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016887:Cardiopulmonary Resuscitation / Q000379:methods / Q000401:mortality; D015331:Cohort Studies; D016001:Confidence Intervals; D004631:Emergency Medical Service Communication Systems / Q000458:organization & administration; D004632:Emergency Medical Services; D005500:Follow-Up Studies; D016015:Logistic Models; D016017:Odds Ratio; D058687:Out-of-Hospital Cardiac Arrest / Q000401:mortality / Q000628:therapy; D036301:Qualitative Research; D012111:Residence Characteristics; D018570:Risk Assessment; D016019:Survival Analysis; D016896:Treatment Outcome; D014861:Washington
keywords: Cardiac arrest; Epidemiology; Ethics; Hawthorne effect; Waiver of consent