The British Medical Journal on Tuesday published an in-depth review examining the extent, causes, and consequences of unpublished evidence, claiming a large proportion of evidence from human trials is unreported, and much of what is reported is done so inadequately.

The journal is calling for more robust regulation and full access to raw trial data to allow drugs to be independently assessed.

One study included in the BMJ review found that fewer than half of U.S. National Institutes of Health funded trials are published in a peer reviewed journal within 30 months of completion, and a second found that only 22 percent of trials subject to mandatory reporting had results available within one year of completion.

The review also includes a study that found including unpublished data in published meta-analyses of drug trials often changed their results.

"When the word 'mandatory' turns out to mandate so little, the need for stronger mechanisms of enforcement becomes very clear," wrote Dr. Richard Lehman from the University of Oxford and BMJ Clinical Epidemiology Editor, Dr. Elizabeth Loder.

"These changes have long been called for, and delay has already caused harm. The evidence we publish shows that the current situation is a disservice to research participants, patients, health systems, and the whole endeavor of clinical medicine."