title: Reporting on blinding in trial protocols and corresponding publications was often inadequate but rarely contradictory.
abstract: OBJECTIVE
  To compare the reporting on blinding in protocols and articles describing randomized controlled trials.
  
  
  METHODS
  We studied 73 protocols of trials approved by the scientific/ethical committees for Copenhagen and Frederiksberg, 1994 and 1995, and their corresponding publications.
  
  
  RESULTS
  Three out of 73 trials (4%) reported blinding in the protocol that contradicted that in the publication (e.g., "open" vs. "double blind"). The proportion of "double-blind" trials with a clear description of the blinding of participants increased from 11 out of 58 (19%) when based on publications alone to 39 (67%) when adding the information in the protocol. The similar proportions for the blinding of health care providers were 2 (3%) and 22 (38%); and for the blinding of data collectors, they were 8 (14%) and 14 (24%). In 52 of 58 publications (90%), it was unclear whether all patients, health care providers, and data collectors had been blinded. In 4 of the 52 trials (7%), the protocols clarified that all three key trial persons had been blinded.
  
  
  CONCLUSIONS
  The reporting on blinding in both trial protocols and publications is often inadequate. We suggest developing international guidelines for the reporting of trial protocols and public access to protocols.
authors.affiliation: The Nordic Cochrane Centre, Rigshospitalet, Copenhagen, Denmark. ah@cochrane.dk
authors.forename: Asbjørn
authors.initials: A
authors.lastname: Hróbjartsson
authors.forename: Julie
authors.initials: J
authors.lastname: Pildal
authors.forename: An-Wen
authors.initials: AW
authors.lastname: Chan
authors.forename: Mette T
authors.initials: MT
authors.lastname: Haahr
authors.forename: Douglas G
authors.initials: DG
authors.lastname: Altman
authors.forename: Peter C
authors.initials: PC
authors.lastname: Gøtzsche
mesh_terms: D002985:Clinical Protocols; D004311:Double-Blind Method; D006801:Humans; D010506:Periodicals as Topic / Q000592:standards; D011643:Publishing / Q000592:standards*; D016032:Randomized Controlled Trials as Topic / Q000379:methods* / Q000592:standards; D012107:Research Design