title: Publication bias of randomized controlled trials in emergency medicine.
abstract: OBJECTIVE
  To determine the publication status and time to publication of randomized controlled trials (RCTs) that were presented at the Society for Academic Emergency Medicine (SAEM) meetings from 1995 to 2003. The impact of positive-outcome bias, time-lag bias, and gray literature bias also was assessed.
  
  
  METHODS
  Retrospective cohort study of RCT abstracts presented at nine SAEM scientific meetings. Electronic searches identified publications from the abstracts.
  
  
  RESULTS
  Of 4,399 abstracts, 383 (8.7%; 95% confidence interval [CI] = 7.8% to 9.5%) were identified as RCTs. One hundred ninety-four (50.7%; 95% CI = 45.7% to 55.7%) were subsequently published up to May 2004. The median time to publication was 32 months (95% CI = 23 to 41), with 59% of RCT abstracts published within five years of presentation. No evidence of positive-outcome bias or time-lag bias was identified; however, changes from abstract to manuscript were found. Manuscripts were less likely to endorse the experimental intervention than were abstracts (OR, 0.2; 95% CI = 0.0 to 0.6).
  
  
  CONCLUSIONS
  The proportion of emergency medicine RCT abstracts published is slightly lower than that for other biomedical specialties; however, biases reported by investigators in other biomedical areas do not appear to be as problematic in emergency medicine research. Differences between conclusions from abstracts and manuscripts must be considered when employing meeting abstracts as a source of evidence for future research or for systematic reviews in emergency medicine.
authors.affiliation: University of Alberta Evidence-based Practice Centre, Department of Emergency Medicine, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Maria B
authors.initials: MB
authors.lastname: Ospina
authors.forename: Karen
authors.initials: K
authors.lastname: Kelly
authors.forename: Terry P
authors.initials: TP
authors.lastname: Klassen
authors.forename: Brian H
authors.initials: BH
authors.lastname: Rowe
mesh_terms: D000043:Abstracting and Indexing; D015982:Bias; D015331:Cohort Studies; D003226:Congresses as Topic; D004635:Emergency Medicine / Q000706:statistics & numerical data*; D006801:Humans; D017594:Publication Bias / Q000706:statistics & numerical data*; D011786:Quality Control; D016032:Randomized Controlled Trials as Topic / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D012955:Societies, Medical