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    Global Database Assessing Pain Trial Results Shows Significant Gaps in Reporting of Study Results

    May 14, 2014 (San Francisco, CA)

    Results from more than half of clinical trials for common chronic pain disorders on the world’s registries are not readily available, according to an updated and thorough analysis.

    Global results from the Repository of Registered Analgesic Clinical Trials (RReACT) database were published online today in the journal PAIN®.

    To capture a snapshot of registered clinical trials related to neuropathic pain and a scorecard of the availability of trial results, Michael Rowbotham (MD)— Scientific Director of the California Pacific Medical Center Research Institute (CPMCRI) and lead study author—and colleagues created RReACT in 2012, a project of the Analgesic Clinical Trial Translations, Innovations, Opportunities and Networks (ACTTION). The updated survey includes results from trials of 15 major registries accessible through the World Health Organization (WHO)’s International Clinical Trials Registry Platform (ICTRP).

    “By initiating RReACT, our goal was to enable greater public access to the results of clinical research,” said Dr. Rowbotham.

    Clinical trials conducted in the US are required to be registered on— the world’s largest global registry and a service of the National Institutes of Health (NIH)—and certain categories of industry-sponsored trial results must be posted within one year of a study’s completion.

    Earlier findings published by Dr. Rowbotham and colleagues included a survey of the results from postherpetic neuralgia, fibromyalgia, and diabetic peripheral neuropathy trials registered on In the present study, they analyzed trial registration, registry functionality, and results reporting on all 15 primary registries in the ICTRP for these three most frequently studied pain disorders. Trial results were searched for in the peer-reviewed literature and the ‘grey literature’ (conference abstracts and/or posters, and press releases), and only unique trials were analyzed.

    In the new project, the researchers identified 447 unique trials, 86 (19%) of which were located on multiple registries. contained 82% of all trials analyzed. Overall, only 46% of all trials had results available, and peer-reviewed publications could be found for a disappointing 30% of trials.

    “Creating a global database of registered trials proved surprisingly difficult for several reasons,” said Dr. Rowbotham. “Because the ICTRP does not reliably identify trials listed on multiple registries, manual searches are necessary. Additionally, searching ICTRP in its entirety yields different results than searching individual registries, and outcome measure descriptions for multiply registered trials vary across registries.”

    According to Dr. Rowbotham, the grey literature is not peer-reviewed nor consistently archived or indexed, and is therefore an unreliable and impermanent source of findings.

    “Analyses and reviews of published evidence need to consider not only the absence of over half of findings, but also the known problem of publication bias,” said Dr. Rowbotham, referring to the phenomenon in which positive results from clinical trials are more likely to be published, and studies with negative findings (in the researchers’ evaluation) are often published in ways that convey positive outcome.

    “There is a significant public health benefit to providing a full picture of trial results to patients,” said Dr. Rowbotham. “Many patients enter clinical trials with the belief that by taking part in research, they will help other patients in the future. For that to happen, the results of this research must be transparent and fully available.”

    The next steps of the research will be to expand the range of painful disorders analyzed, and update the scorecards.

    The study was funded by the ACTTION initiative, a public-private partnership between the FDA, NIH, industry, and academia. The RReACT database is freely accessible via the ACTTION website (