title: The Quality of the Evidence According to GRADE Is Predominantly Low or Very Low in Oral Health Systematic Reviews.
abstract: OBJECTIVE
  The main objective was to assess the credibility of the evidence using Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) in oral health systematic reviews on the Cochrane Database of Systematic Reviews (CDSR) and elsewhere.
  
  
  METHODS
  Systematic Reviews or meta-analyses (January 2008-December 2013) from 14 high impact general dental and specialty dental journals and the Cochrane Database of Systematic Reviews were screened for meta-analyses. Data was collected at the systematic review, meta-analysis and trial level. Two reviewers applied and agreed on the GRADE rating for the selected meta-analyses.
  
  
  RESULTS
  From the 510 systematic reviews initially identified 91 reviews (41 Cochrane and 50 non-Cochrane) were eligible for inclusion. The quality of evidence was high in 2% and moderate in 18% of the included meta-analyses with no difference between Cochrane and non-Cochrane reviews, journal impact factor or year of publication. The most common domains prompting downgrading of the evidence were study limitations (risk of bias) and imprecision (risk of play of chance).
  
  
  CONCLUSIONS
  The quality of the evidence in oral health assessed using GRADE is predominantly low or very low suggesting a pressing need for more randomised clinical trials and other studies of higher quality in order to inform clinical decisions thereby reducing the risk of instituting potentially ineffective and/or harmful therapies.
authors.affiliation: Department of Hygiene and Epidemiology, Medical School, University of Ioannina, 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, Turner St., London E1 2 AD, 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, Coupland 3 Building, Oxford Road, Manchester, M13 9PL, United Kingdom.
authors.forename: Helen
authors.initials: H
authors.lastname: Worthington
authors.affiliation: Department of Hygiene and Epidemiology, Medical School, University of Ioannina, Ioannina, Greece.
authors.forename: Georgia
authors.initials: G
authors.lastname: Salanti
mesh_terms: D019317:Evidence-Based Medicine / Q000592:standards*; D006801:Humans; D055811:Journal Impact Factor; D015201:Meta-Analysis as Topic; D009909:Oral Health; D012196:Review Literature as Topic; D015983:Selection Bias