It adds that European Union guidelines require researchers to report clinical trial results to the European Union Clinical Trials Register (EUCTR) within a year of the trial's end. A University of Oxford-led team has now examined how well researchers comply with this guideline.
As they report in the BMJ, Oxford's Ben Goldacre and his colleagues sifted through 11,531 trials listed as completed at EUCTR. Of those, 7,274 trials had their results due, but only about half had reported their results.
However, trials with a commercial sponsor were more likely than others to report results, the researchers found. They report that 68 percent of commercial trial sponsors reported their results within a year, while only 11 percent of non-commercial trial sponsors did. About 10 sponsors — all commercial — have a 100 percent reporting rate, while about two dozen — mostly universities, hospitals, or research institutes — have a zero percent reporting rate.
"This problem strikes to the heart of evidence based medicine," Goldacre, the director of Oxford's DataLab, says in a statement. "We cannot make informed choices about which treatments work best, as doctors and patients, unless all results are reported."