Study: Clinical trial data not being published
Almost 30% of completed studies registered at ClinicalTrials.gov fail to achieve published disclosure of result (PDOR) within four years of completion, a new study found.
The 2007 Food and Drug Administration Amendments Act requires that certain clinical trials and research studies involving human subjects be registered on ClinicalTrials.gov, and results published on the website and/or in scientific journals within a year of completion. Phase 1 studies and those products at the pre-licensure stage are exempt, the authors say. "Failure of transparency conflicts with the bedrock ethical principles governing clinical research (justice, beneficence and respect for subjects), and, by risking reporting bias, undermines the validity of the scientific literature. Promoting transparency in clinical trials is an intrinsic public health good," the study authors explained.1
PDOR is critical for clinical trial results transparency, the authors wrote.1
In the study, published in PLoS One in July, the authors analyzed data from 400 studies registered to ClinicalTrials.gov that had been completed for at least four years, in an effort to measure transparency in clinical trials. The 400 randomly selected clinical trials were completed between Jan. 1, 2012 and Dec. 31, 2012. The authors determined that PDOR was achieved if the completed study results were published by Jan. 6, 2013, and PDOR failed if results were not published at all.
Of the 400 studies, 247 were industry funded, 106 had no industry funding, and 47 had multiple funding sources. Fifty-two percent were Phase 2 studies, while 48% were Phase 3 and 4 studies. The median day from PDOR to publication and/or posting of results was 602 days. Industry-funded studies were less likely to be published than studies with other funding sources.1
"Our analysis suggests that a high proportion of completed U.S.-based human subjects clinical trials did not achieve timely transparency either through publication in peer-review journals or by posting basic results to CTG [ClinicalTrials.gov], or PDOR as defined in this article," the authors wrote. "Moreover, the probability that a given study achieves PDOR varied significantly as a function of study funding source, phase of development, and other factors: studies were less likely to achieve PDOR if at phase 2, were randomized, involved only adult subjects, and had smaller sample sizes."1
To reduce reporting bias and increase transparency in clinical trial results, the authors suggested requiring the posting of Phase 1 studies to ClinicalTrials.gov; pressure from outside sources, such as medical journals, to only publish studies that have registered to ClinicalTrials.gov within five years of completion; and for ClinicalTrials.gov to send email reminders to investigators to post for studies that are complete.
"[T]he current status quo violates our ethical obligation to study subjects who would likely be dismayed to learn that the results from those studies might never enter the public domain," the authors wrote. "Given the evident need to protect fidelity of the scientific literature and the need to maintain the public’s faith in clinical research, it is essential that the research community unite around the common goal of maximizing transparency."1
- Saito H, Gill CJ (2014) How Frequently Do the Results from Completed US Clinical Trials Enter the Public Domain? - A Statistical Analysis of the ClinicalTrials.gov Database. PLoS ONE 9(7): e101826. doi:10.1371/journal.pone.0101826.
