Although randomized trials provide key guidance for how we practice medicine, trust in their published results has been eroded in recent years due to several high-profile cases of alleged data suppression, misrepresentation, and manipulation [1–5, 39]. While most publicized cases have involved pharmaceutical industry trials, accumulating empiric evidence has shown that selective reporting of results is a systemic problem afflicting all types of trials, including those with no commercial input . These examples highlight the harmful potential impact of biased reporting on patient care, and the violation of ethical responsibilities of researchers and sponsors to disseminate results accurately and comprehensively.
Biased reporting arises when two main decisions are made based on the direction and statistical significance of the data—whether to publish the trial at all, and if so, which analyses and results to report in the publication. Strong evidence for the selective publication of positive trials has been available for decades [7,8]. More recent cohort studies have focused on the misreporting of trials within publications by comparing journal articles either with documents from regulatory agencies [9–12] or with trial protocols from research ethics committees [13–16], funding agencies , research groups [18,19], and journals . These cohort studies identified major discrepancies—favorable results were often highlighted while unfavorable data were suppressed; definitions of primary outcomes were changed; and methods of statistical analysis were modified without explanation in the journal article.
…Overall, a substantial amount of primary outcome data submitted to the FDA was found to be missing from the literature. One quarter of trials in their sample were unpublished—predominantly those with unfavorable results. Not only were data suppressed for the unpublished trials, but an additional quarter of primary outcomes were omitted from journal articles of published trials. These findings are consistent with two recent reviews of FDA documents and journal articles [10,21], one of which was published in PLoS Medicine in September 2008 .