GRADE guidelines: 5. Rating the quality of evidence--publication bias.

TitleGRADE guidelines: 5. Rating the quality of evidence--publication bias.
Publication TypeJournal Article
Year of Publication2011
AuthorsGuyatt GH, Oxman AD, Montori V, Vist G, Kunz R, Brozek J, Alonso-Coello P, Djulbegovic B, Atkins D, Falck-Ytter Y, Williams JW, Meerpohl J, Norris SL, Akl EA, Sch├╝nemann HJ
JournalJournal of clinical epidemiology
Date Published2011 Dec
KeywordsCross-Sectional Studies; Drug Industry; Evidence-Based Medicine; Meta-Analysis as Topic; Practice Guidelines as Topic; Publication Bias; Randomized Controlled Trials as Topic; Review Literature as Topic; Statistics as Topic

In the GRADE approach, randomized trials start as high-quality evidence and observational studies as low-quality evidence, but both can be rated down if a body of evidence is associated with a high risk of publication bias. Even when individual studies included in best-evidence summaries have a low risk of bias, publication bias can result in substantial overestimates of effect. Authors should suspect publication bias when available evidence comes from a number of small studies, most of which have been commercially funded. A number of approaches based on examination of the pattern of data are available to help assess publication bias. The most popular of these is the funnel plot; all, however, have substantial limitations. Publication bias is likely frequent, and caution in the face of early results, particularly with small sample size and number of events, is warranted.

Alternate JournalJ Clin Epidemiol