I recently came across this article from last summer: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0101826. It presents an analysis of the frequency with which data from completed clinical trials (in the US) actually make it into the public domain, which the authors define as publication of the primary outcome in a peer-reviewed journal and/or posting of the data to ClinicalTrials.gov. The studies had to be interventional, at least Phase II, and listed on ClinicalTrials.gov as having been completed in 2008. That year was chosen as it was the first year in which the Food and Drug Administration Amendment Act (FDAAA) requirements on posting of clinical trials data within 1 year of completion (except Phase I, and except for products pre-licensure) came into effect. A total of 400 randomly-selected studies—from both industry and non-industry, and a mixture of the two, funding sources—fulfilling the pre-defined criteria were selected, and a 4-year follow-up period was used.
To cut a long story short, the data are not marvellous. The analysis showed a widespread failure to publically disclose results, with data for nearly 30% of the 400 studies that were included neither having been posted nor published within 4 years of completion of the study. For those that were disclosed publically, the median time taken from the end of the study was around 600 days. That’s pushing 2 years. Also a worry is that industry-funded studies were less likely to be published than studies with non-industry or mixed-funding.
All this is fairly depressing reading, and seems to show that publication bias is alive and kicking. But we should remember that this analysis was conducted on studies completed in 2008, the first year of the FDAAA requirements being announced. We are all aware of historic poor publication practices, and changing that mind-set is no mean feat. But with the advent of Good Publication Practice, the FDAAA requirements, and the much-increased reach of organisations such as the International Society for Medical Publication Professionals in recent years, it is to be hoped that things are now moving in the right direction. It would be interesting to see this analysis on a rolling annual basis, to hopefully see the momentum gained now that this particular oil tanker is underway. Hopefully we’d see more and more data being released into the public domain in a timely and transparent manner, reducing publication bias.