About 30 percent of large clinical trials registered with ClinicalTrials.gov go unpublished, report Christopher Jones from Cooper Medical School of Rowan University in New Jersey and his colleagues in the British Medical Journal.
They sorted through trials involving more than 500 participants that were prospectively included in the database and that were completed by January 2009. Of the 585 trials they homed in on, the results from 171 had not been published by November 2012.
Part of the social contract of clinical trials, Jones and his colleagues write, is that although participants themselves may not benefit from the study, society will when the results are made known. "The non-publication of trial data … violates an ethical obligation that investigators have towards study participants," Jones et al. say. "When trial data remain unpublished, the societal benefit that may have motivated someone to enroll in a study remains unrealized."
Of those 171 unpublished trials, 133 had no data in ClinicalTrials.gov itself. In addition, Jones and his colleagues found that the lack of publication was more common in industry-sponsored trials — 32 percent — than non-industry sponsored ones —18 percent.
"There's no excuse for not publishing results but a huge public health benefit to having a complete picture of what was found in trials conducted on treatments currently available to patients," Síle Lane from the UK group Sense about Science tells the Guardian.