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Non-publication is more common among industry-funded trials, study finds.

A new analysis of 585 large, randomized clinical trials registered with ClinicalTrials.gov finds that 29 percent have not been published in scientific journals. In addition, nearly 78 percent of the unpublished trials had no results available on the website, either.

As a result, nearly 300,000 people who were enrolled in the 171 unpublished trials "were exposed to the risks of trial participation without the societal benefits which accompany the dissemination of trial results," said Christopher W. Jones, MD, a former resident physician at University of North Carolina School of Medicine who is now an attending physician at Cooper Medical School of Rowan University in Camden, N.J. and lead author of the study published in the Oct. 29, 2013 issue of the British Medical Journal.

Non-publication of clinical trials has been a controversial issue in recent years. In particular, industry-funded clinical trials - such as those paid for by pharmaceutical companies - have come under fire on allegations that such trials are often not published when the results are not favorable to the drug or other product being tested.

Against this background, the study authors set out to determine what happened to 585 large, randomized trials with at least 500 participants that were registered with ClinicalTrials.gov and completed before January 2009. ClinicalTrials.gov is a website that provides patients, their family members, health care professionals, researchers and the public with easy access to information on publicly and privately supported clinical studies on a wide range of diseases and conditions.

Of the 585 registered trials, 171 (29 percent) had not been published by November 2012, when the final literature search for this study was conducted. Non-publication was more common among trials that received industry funding (32 percent ) compared to those without industry funding (18 percent). Of the 171 unpublished trials, 133 (78 percent) had no results available in ClinicalTrials.gov.

"Clinical trials are an essential source of information for how to care for patients. Additional policies are needed to ensure that results of all large clinical trials are made publicly available in a timely manner," said Timothy F. Platts-Mills, MD, an assistant professor of emergency medicine at UNC and senior author of the study.

Co-authors of the study, all at UNC, are Lara Handler, Karen E. Crowell, Lukas G. Keil, and Mark A. Weaver, PhD, research assistant professor in the UNC School of Medicine and the UNC Gillings School of Global Public Health.