Clinical trials subject to publication bias

Clinical question: 
Is publication of clinical trials influenced by the statistical significance, perceived importance or direction of their results?
Bottom line: 
Trials with positive findings are published more often, and more quickly, than trials with negative findings. The authors of the review predicted, if 41% of negative trials were published, they would expect 73% of positive trials to be published. The size of the trial and the source of funding, academic rank, and sex of the principal investigator did not appear to influence whether a trial was published. The prospective registration of all clinical trials at inception and before their results become available would enable review authors to know when relevant trials have been conducted, so that they could ask the responsible investigators for the relevant study data.
Caveat: 
Those conducting systematic reviews should ensure they assess the potential problems of publication bias in their review, and consider methods for addressing this issue by ensuring a comprehensive search for both published and unpublished trials.
Context: 
The tendency for authors to submit manuscripts, and of journals to accept manuscripts for publication based on the direction or strength of the study findings, has been termed publication bias. Such bias can threaten the validity of a systematic review's conclusions.
Review CD#: 
CD000006
PEARLS No: 
164
Date: 
April, 2009
Authored by: 
Brian R McAvoy