title: Outcome discrepancies and selective reporting: impacting the leading journals?
abstract: BACKGROUND
  Selective outcome reporting of either interesting or positive research findings is problematic, running the risk of poorly-informed treatment decisions. We aimed to assess the extent of outcome and other discrepancies and possible selective reporting between registry entries and published reports among leading medical journals.
  
  
  METHODS
  Randomized controlled trials published over a 6-month period from July to December 31st, 2013, were identified in five high impact medical journals: The Lancet, British Medical Journal, New England Journal of Medicine, Annals of Internal Medicine and Journal of American Medical Association were obtained. Discrepancies between published studies and registry entries were identified and related to factors including registration timing, source of funding and presence of statistically significant results.
  
  
  RESULTS
  Over the 6-month period, 137 RCTs were found. Of these, 18% (n = 25) had discrepancies related to primary outcomes with the primary outcome changed in 15% (n = 20). Moreover, differences relating to non-primary outcomes were found in 64% (n = 87) with both omission of pre-specified non-primary outcomes (39%) and introduction of new non-primary outcomes (44%) common. No relationship between primary or non-primary outcome change and registration timing (prospective or retrospective; P = 0.11), source of funding (P = 0.92) and presence of statistically significant results (P = 0.92) was found.
  
  
  CONCLUSIONS
  Discrepancies between registry entries and published articles for primary and non-primary outcomes were common among trials published in leading medical journals. Novel approaches are required to address this problem.
authors.affiliation: Oral Growth and Development, Barts and The London School of Medicine and Dentistry, Institute of Dentistry, Queen Mary University of London, London, England.
authors.forename: Padhraig S
authors.initials: PS
authors.lastname: Fleming
authors.affiliation: Department of Orthodontics, University of Athens, Athens, Greece.
authors.forename: Despina
authors.initials: D
authors.lastname: Koletsi
authors.affiliation: Institute of Translational Medicine, University of Liverpool, Liverpool, England.
authors.forename: Kerry
authors.initials: K
authors.lastname: Dwan
authors.affiliation: Department of Orthodontics and Dentofacial Orthopedics, Dental School/Medical Faculty, University of Bern, Bern, Switzerland.
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Pandis
mesh_terms: D006801:Humans; D010506:Periodicals as Topic / Q000592:standards*; D017594:Publication Bias; D016032:Randomized Controlled Trials as Topic; D012042:Registries; D012107:Research Design / Q000592:standards*