Nearly 30% of all large clinical trials in the United States have gone unpublished five years after their completion, often because those running them—pharmaceutical companies—don’t want their results known.

This failure to share information represents an ethical violation on the part of companies and organizations that are obligated to tell trial participants about testing results, scientists wrote in the British Medical Journal.

These experts say approximately 250,000 people took part in the 29% of trials that haven’t been published. Considering only those trials funded by the pharmaceutical industry, the number rose to 32%.

This “violates an ethical obligation that investigators have towards study participants,” Christopher Jones of Cooper Medical School of Rowan University, New Jersey, who worked on the study, told The Guardian.

Jones and his colleagues said changes must be made “to ensure timely public dissemination of trial data.”

Pharmaceutical manufactures are currently required to register all trials and report their results with the government through the database Clinicaltrials.gov. It is a global register and the largest such database in the world. But the study demonstrates that many companies are ignoring this requirement.

Síle Lane, director of campaigns at the U.K.-based AllTrials Campaign, told The Guardian that database postings are critical to science and, consequently, to patients. “There’s no excuse for not publishing results but a huge public health benefit to having a complete picture of what was found in trials conducted on treatments currently available to patients,” she said. “[For example,] trials from around the world are used to make UK prescribing decisions. So information from those trials is vital for UK regulators and researchers.”

Drug makers are sometimes motivated to not publish clinical trial information in order to hide details of side effects or outright failures of new treatments. They also try to avoid disclosing data that might help their competition.

Richard Stephens, a cancer patient who has been in five trials, told The Guardian that it’s important for testing to be made public.

“I would ask every researcher and every research funder out there to do all they can to make their results available. Patients become participants to add to knowledge and to eliminate uncertainties. Hiding results, no matter what the reason, isn’t in that spirit at all. In fact it is a betrayal of our trust,” Stephens said.

-Noel Brinkerhoff

To Learn More:

Scientists Alarmed Over Ethics of Drug Trials Remaining Unpublished Up to Five Years After They’re Finished (by Sarah Boseley, The Guardian)

Non-Publication of Large Randomized Clinical Trials: Cross Sectional Analysis (by Christopher W. Jones, Lara Handler, Karen E. Crowell, Lukas G. Keil, Mark A. Weaver, Timothy F Platts-Mills; British Medical Journal)

Big Drug Firms Mobilize Patient Groups to Lobby against Publication of Secret Drug Testing Data (by Noel Brinkerhoff, AllGov)

Drug Companies Still Outsourcing Dangerous Trials to Poor Nations (by Noel Brinkerhoff and David Wallechinsky, AllGov)