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J Clin Epidemiol. 2011 Dec;64(12):1277-82. doi: 10.1016/j.jclinepi.2011.01.011. Epub 2011 Jul 30.

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

Author information

1
Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario L8N 3Z5, Canada. guyatt@mcmaster.ca

Abstract

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.

PMID:
21802904
DOI:
10.1016/j.jclinepi.2011.01.011
[Indexed for MEDLINE]

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