http://www.sciencedaily.com/releases/2009/01/
     090120204807.htmClinical Trials: Unfavourable Results Often Go Unpublished

				ScienceDaily (Jan. 21, 2009)
— Trials showing a positive treatment effect, or those with important
or striking findings, were much more likely to be published in
scientific journals than those with negative findings, a new review
from The Cochrane Library has found.
				
				

				
"This publication bias has important implications for healthcare.
Unless both positive and negative findings from clinical trials are
made available, it is impossible to make a fair assessment of a drug's
safety and efficacy," says lead researcher, Sally Hopewell of the UK
Cochrane Centre in Oxford, UK.
The international team of researchers carried out a systematic
review of all the existing research in this area. In addition to
showing that negative results were published less often, they found
that if these results were eventually published, they would take
between one and four more years to appear in journals than studies
showing positive results.
Results from one of the five studies in the review indicated that
investigators and not editors might be to blame. The reasons most
commonly given for not publishing were that investigators thought their
findings were not interesting enough or did not have time. "The
registration of all clinical trial protocols before they start should
make it easier to identify where we are missing results," says Kay
Dickersin from Johns Hopkins University in Baltimore, USA, another of
the researchers on this project.
One of the other researchers, Kirsty Loudon, based in Scotland,
adds, "Registration of trials and their results would help people
conducting systematic reviews to look at both published and unpublished
evidence, to reach reliable conclusions."
The researchers say their study also highlights the need for a
worldwide commitment to the disclosure of the findings of clinical
trials. Mike Clarke of Trinity College Dublin in Ireland, says, "The
World Health Organisation recently found widespread support for the
development of such a process."
Andy Oxman from the Norwegian Knowledge Centre for Health Services
concludes, "Healthcare decisions need to be based on all the evidence,
not just the most exciting results."
				
				
				
				Journal reference:
Hopewell S, Loudon K, Clarke MJ, Oxman AD, Dickersin K. Publication bias in clinical trials due to statistical significance or direction of trial results. Cochrane Database of Systematic Reviews, Issue 1. Art. No.: MR000006 DOI: 0.1002/14651858.MR000006.pub3

				
				Adapted from materials provided by Wiley-Blackwell, via EurekAlert!, a service of AAAS.
				
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							Wiley-Blackwell (2009, January 21). Clinical Trials: Unfavourable Results Often Go Unpublished. ScienceDaily. Retrieved January 22, 2009, from http://www.sciencedaily.com­ /releases/2009/01/090120204807.htm
							

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