title: Methodology-dependent variation in documentation of outcome predictors in out-of-hospital cardiac arrest.
abstract: OBJECTIVE
  To identify variation in outcome predictor documentation in out-of-hospital cardiac arrest associated with two different methods of data collection: concurrent questioning of personnel following a resuscitation attempt and archival report review.
  
  
  METHODS
  All patients > or = 18 years old who had out-of-hospital cardiac arrests, verified using the New York City 911 telephone system, between October 1, 1990, and April 1, 1991, were eligible for inclusion. The authors reviewed the first 200 cases of presumed primary cardiac arrest involving a resuscitation attempt among 3,243 consecutive ambulance call reports for cardiac arrest occurring during the study period. This archival data set was compared with data for the same 200 cases gathered through direct interview of field personnel by trained paramedics. The two data sets had been compiled independently by different individuals, using the same data collection instrument, which conformed to the Utstein template.
  
  
  RESULTS
  Comparison of the data obtained from ambulance records with the data obtained from interviews of prehospital personnel revealed several areas of variance. Of note was a significantly lower proportion of bystander-witnessed ventricular fibrillation (VF) in the data set gathered from written reports (7% vs 18%; 95% CI for the difference 4-18%; p = 0.001).
  
  
  CONCLUSIONS
  differences in methods of collection of out-of-hospital cardiac arrest data are associated with a more than twofold variation in the reported incidences of witnessed cardiac arrests manifesting as VF. Methodology-dependent variation in this important "denominator" may produce substantially different estimates of survival within the same cohort of patients.
authors.affiliation: Department of Medicine, Albert Einstein College of Medicine, USA.
authors.forename: E J
authors.initials: EJ
authors.lastname: Gallagher
authors.forename: G
authors.initials: G
authors.lastname: Lombardi
authors.forename: P
authors.initials: P
authors.lastname: Gennis
authors.forename: M
authors.initials: M
authors.lastname: Treiber
mesh_terms: D000328:Adult; D016887:Cardiopulmonary Resuscitation; D003625:Data Collection; D004282:Documentation; D006323:Heart Arrest / Q000401:mortality / Q000628:therapy; D006801:Humans; D011379:Prognosis; D011446:Prospective Studies; D015996:Survival Rate; D016896:Treatment Outcome