title: Reporting of eligibility criteria of randomised trials: cohort study comparing trial protocols with subsequent articles.
abstract: OBJECTIVE
  To determine whether and how eligibility criteria of participants prespecified in protocols of randomised trials are reported in subsequent articles.
  
  
  METHODS
  Cohort study.
  
  
  METHODS
  Protocols submitted to the ethics committee of a German medical faculty.
  
  
  METHODS
  52 trial protocols and 78 subsequent publications published between 2000 and 2006.
  
  
  METHODS
  Proportion of matching, missing, modified, or newly added eligibility criteria between trial protocols and subsequent publications.
  
  
  RESULTS
  Differences were found between protocols and subsequent publications for all 52 trials. Information on eligibility criteria was missing in the publications for all 52 trials (100%, 95% confidence interval 93% to 100%), modified for 44 (85%, 72% to 93%), and newly added for 21 (41%, 27% to 55%). The mean number of eligibility criteria for each trial was 25 (range 7-43) and the mean proportion of matching eligibility criteria per trial was 50% (95% confidence interval 44% to 55%, range 13-93). Of 1248 eligibility criteria prespecified in the protocols, 606 (49%, 46% to 51%) were matching in subsequent publications, 479 (38%, 36% to 41%) were missing, and 163 (13%, 11% to 15%) were modified. 51 eligibility criteria were added to publications. Most prespecified eligibility criteria were about comorbidity (42%, 39% to 45%), treatment (20%, 18% to 22%), or type or severity of illness (17%, 15% to 19%). Most of the missing eligibility criteria (96%, 94% to 97%) and modified eligibility criteria (54%, 46% to 62%) suggested broader study populations and most of the added eligibility criteria (86%, 74% to 94%) suggested narrower study populations.
  
  
  CONCLUSIONS
  Many users of trial information rely on published journal articles. These articles generally do not reflect the exact definition of the study population as prespecified in the protocol. Incomplete or inadequate reporting of eligibility criteria hampers a proper assessment of the applicability of trial results.
authors.affiliation: Department of Medical Biometry and Statistics, Institute of Medical Biometry and Medical Informatics, University Medical Center Freiburg, German Cochrane Center, Berliner Allee 29, 79110 Freiburg, Germany. bluemle@cochrane.de
authors.forename: Anette
authors.initials: A
authors.lastname: Blümle
authors.forename: Joerg J
authors.initials: JJ
authors.lastname: Meerpohl
authors.forename: Gerta
authors.initials: G
authors.lastname: Rücker
authors.forename: Gerd
authors.initials: G
authors.lastname: Antes
authors.forename: Martin
authors.initials: M
authors.lastname: Schumacher
authors.forename: Erik
authors.initials: E
authors.lastname: von Elm
mesh_terms: D002985:Clinical Protocols; D015331:Cohort Studies; D006801:Humans; D018579:Patient Selection; D016032:Randomized Controlled Trials as Topic; D012107:Research Design; D015983:Selection Bias