title: Validity of randomized clinical trials in gastroenterology from 1964-2000.
abstract: OBJECTIVE
  The internal validity of clinical trials depends on the adequacy of the reported methodological quality. We assessed the methodological quality of all 383 randomized clinical trials published in GASTROENTEROLOGY as original articles from 1964 to 2000.
  
  
  METHODS
  The methodological quality (randomization and blinding), sample size, publication year, and disease area were extracted from each trial. Changes during the study period were analyzed by analysis of variance with adjustments for potential confounders.
  
  
  RESULTS
  Forty-two percent of all trials reported adequate generation of the allocation sequence, 39% reported adequate allocation concealment, and 62% were double blind. The reported methodological quality improved significantly in the mid-1990s.
  
  
  CONCLUSIONS
  The present study shows a positive development, but the reported methodological quality of trials can still be improved.
authors.affiliation: The Cochrane Hepato-Biliary Group, Copenhagen Trial Unit, Center for Clinical Intervention Research, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Lise L
authors.initials: LL
authors.lastname: Kjaergard
authors.forename: Sarah L
authors.initials: SL
authors.lastname: Frederiksen
authors.forename: Christian
authors.initials: C
authors.lastname: Gluud
mesh_terms: D005762:Gastroenterology; D006801:Humans; D016032:Randomized Controlled Trials as Topic / Q000592:standards*; D015203:Reproducibility of Results