title: GRADE guidelines: 3. Rating the quality of evidence.
abstract: This article introduces the approach of GRADE to rating quality of evidence. GRADE specifies four categories-high, moderate, low, and very low-that are applied to a body of evidence, not to individual studies. In the context of a systematic review, quality reflects our confidence that the estimates of the effect are correct. In the context of recommendations, quality reflects our confidence that the effect estimates are adequate to support a particular recommendation. Randomized trials begin as high-quality evidence, observational studies as low quality. "Quality" as used in GRADE means more than risk of bias and so may also be compromised by imprecision, inconsistency, indirectness of study results, and publication bias. In addition, several factors can increase our confidence in an estimate of effect. GRADE provides a systematic approach for considering and reporting each of these factors. GRADE separates the process of assessing quality of evidence from the process of making recommendations. Judgments about the strength of a recommendation depend on more than just the quality of evidence.
authors.affiliation: Oregon Evidence-based Practice Center, Oregon Health and Science University, 3181 SW Sam Jackson Park Rd., Portland, OR 97239, USA. balshemh@ohsu.edu
authors.forename: Howard
authors.initials: H
authors.lastname: Balshem
authors.forename: Mark
authors.initials: M
authors.lastname: Helfand
authors.forename: Holger J
authors.initials: HJ
authors.lastname: Schünemann
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Oxman
authors.forename: Regina
authors.initials: R
authors.lastname: Kunz
authors.forename: Jan
authors.initials: J
authors.lastname: Brozek
authors.forename: Gunn E
authors.initials: GE
authors.lastname: Vist
authors.forename: Yngve
authors.initials: Y
authors.lastname: Falck-Ytter
authors.forename: Joerg
authors.initials: J
authors.lastname: Meerpohl
authors.forename: Susan
authors.initials: S
authors.lastname: Norris
authors.forename: Gordon H
authors.initials: GH
authors.lastname: Guyatt
mesh_terms: D019317:Evidence-Based Medicine / Q000592:standards*; D005260:Female; D019983:Guideline Adherence; D006801:Humans; D008297:Male; D017410:Practice Guidelines as Topic / Q000592:standards*; D017594:Publication Bias; D011785:Quality Assurance, Health Care / Q000592:standards*