Recommendations for examining and interpreting funnel plot asymmetry in meta-analyses of randomised controlled trials

• Published in: BMJ Vol. 343; no. 7818; pp. 302 - 307
• Main Authors: Sterne, Jonathan A C, Sutton, Alex J, Ioannidis, John P A, Terrin, Norma, Jones, David R, Lau, Joseph, Carpenter, James, Rücker, Gerta, Harbord, Roger M, Schmid, Christopher H, Tetzlaff, Jennifer, Deeks, Jonathan J, Peters, Jaime, Macaskill, Petra, Schwarzer, Guido, Duval, Sue, Altman, Douglas G, Moher, David, Higgins, Julian P T
• Format: Journal Article
• Language: English
• Published: England British Medical Journal Publishing Group 22.07.2011; BMJ Publishing Group; BMJ Publishing Group LTD
• Subjects: Asymmetry; Bias; Estimates; Estimation bias; Evidence-based medicine; Experimentation; Geometric funnels; Heart attacks; Intervention; Magnesium; Meta analysis; Meta-Analysis as Topic; Randomized Controlled Trials as Topic; Recommendations; Research biases; RESEARCH METHODS & REPORTING; Sampling bias; Selection Bias; Standard error; Statistical bias; Statistics as Topic - methods
• ISSN: 0959-8138; 1468-5833; 1756-1833
• DOI: 10.1136/bmj.d4002

Funnel plots, and tests for funnel plot asymmetry, have been widely used to examine bias in the results of meta-analyses. Funnel plot asymmetry should not be equated with publication bias, because it has a number of other possible causes. This article describes how to interpret funnel plot asymmetry, recommends appropriate tests, and explains the implications for choice of meta-analysis model