title: Discrepancies in Outcome Reporting Exist Between Protocols and Published Oral Health Cochrane Systematic Reviews.
abstract: OBJECTIVE
  To assess discrepancies in the analyzed outcomes between protocols and published reviews within Cochrane oral health systematic reviews (COHG) on the Cochrane Database of Systematic Reviews (CDSR).
  
  
  METHODS
  All COHG systematic reviews on the CDSR and the corresponding protocols were retrieved in November 2014 and information on the reported outcomes was recorded. Data was collected at the systematic review level by two reviewers independently.
  
  
  RESULTS
  One hundred and fifty two reviews were included. In relation to primary outcomes, 11.2% were downgraded to secondary outcomes, 9.9% were omitted altogether in the final publication and new primary outcomes were identified in 18.4% of publications. For secondary outcomes, 2% were upgraded to primary, 12.5% were omitted and 30.9% were newly introduced in the publication. Overall, 45.4% of reviews had at least one discrepancy when compared to the protocol; these were reported in 14.5% reviews. The number of review updates appears to be associated with discrepancies between final review and protocol (OR: 3.18, 95% CI: 1.77, 5.74, p<0.001). The risk of reporting significant results was lower for both downgraded outcomes [RR: 0.52, 95% CI: 0.17, 1.58, p = 0.24] and upgraded or newly introduced outcomes [RR: 0.77, 95% CI: 0.36, 1.64, p = 0.50] compared to outcomes with no discrepancies. The risk of reporting significant results was higher for upgraded or newly introduced outcomes compared to downgraded outcomes (RR = 1.19, 95% CI: 0.65, 2.16, p = 0.57). None of the comparisons reached statistical significance.
  
  
  CONCLUSIONS
  While no evidence of selective outcome reporting was found in this study, based on the present analysis of SRs published within COHG systematic reviews, discrepancies between outcomes in pre-published protocols and final reviews continue to be common. Solutions such as the use of standardized outcomes to reduce the prevalence of this issue may need to be explored.
authors.affiliation: Department of Hygiene and Epidemiology, University of Ioannina School of Medicine, Ioannina, Greece; Department of Orthodontics and Dentofacial Orthopedics, Dental School/Medical Faculty, University of Bern, Bern, Switzerland.
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Pandis
authors.affiliation: Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom.
authors.forename: Padhraig S
authors.initials: PS
authors.lastname: Fleming
authors.affiliation: Cochrane Oral Health Group, School of Dentistry, The University of Manchester, Manchester, United Kingdom.
authors.forename: Helen
authors.initials: H
authors.lastname: Worthington
authors.affiliation: Institute of Translational Medicine, Department of Biostatistics, University of Liverpool, Liverpool, United Kingdom.
authors.forename: Kerry
authors.initials: K
authors.lastname: Dwan
authors.affiliation: Department of Hygiene and Epidemiology, University of Ioannina School of Medicine, Ioannina, Greece.
authors.forename: Georgia
authors.initials: G
authors.lastname: Salanti
mesh_terms: D016206:Databases, Bibliographic; D015201:Meta-Analysis as Topic; D009909:Oral Health; D010506:Periodicals as Topic; D015983:Selection Bias; D000078202:Systematic Reviews as Topic