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Empirical assessment of effect of publication bias on meta-analyses

By Alex J. Sutton, S.J. Duval, R.L. Tweedie, Keith R. Abrams and David R. Jones


Tables and figures are in a separate document available via the BMJ website at, and available here converted to PDF.Objective: To assess the effect of publication bias on the results and conclusions of systematic reviews and\ud meta-­analyses.\ud \ud Design: Analysis of published meta­-analyses by trim and fill method.\ud \ud Studies: 48 reviews in Cochrane Database of\ud Systematic Reviews that considered a binary endpoint and contained 10 or more individual studies.\ud \ud Main outcome measures: Number of reviews with missing studies and effect on conclusions of meta-­analyses.\ud \ud Results: The trim and fill fixed effects analysis method estimated that 26 (54%) of reviews had missing studies and in 10 the number missing was significant. The\ud corresponding figures with a random effects model were 23 (48%) and eight. In four cases, statistical inferences regarding the effect of the intervention were changed after the overall estimate for publication bias was adjusted for.\ud \ud Conclusions: Publication or related biases were common within the sample of meta­analyses assessed. In most cases these biases did not affect the conclusions. Nevertheless, researchers should check\ud routinely whether conclusions of systematic reviews are robust to possible non­random selection mechanisms

Publisher: British Medical Journal
Year: 2000
OAI identifier:

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