Clinical trial registries, such as ClinicalTrials.gov, include less information on harmful side effects than the clinical study reports submitted to regulators as part of new drug applications, according to a new study that urges regulators to make the reports public.

Researchers from the University of Southern Denmark and the University of Paris looked at 42 trials evaluating 13 cancer drugs whose makers were seeking approval from the European Medicines Agency between 2015 and 2018. The researchers then scrutinized data available on side effects caused by the 13 drugs.

The number of deaths caused by adverse events differed between clinical study reports and clinical trial registries in 92 percent of trials, and with journal articles in 40 percent of trials, the researchers say in an article published in the journal BMC Medicine. And the number of deaths due to adverse events was not available at all in ClinicalTrials.gov.

Also, the number of patients with at least one serious adverse event was reported in only half of published journal articles, according to the study.

Additionally, the number of patients stopping treatment with a drug because of adverse events was different in clinical study reports and clinical trial registries for 88 percent of trials that included such information in both sources.

The researchers also found that information about clinical trials was hard to obtain, taking more than two years on average after the end of a trial until results were published in academic journals and more than four years until the reports themselves were made available to the public.

“We consider it vital that regulators start routinely releasing case study reports,” the researchers wrote.

In 2018, the FDA began a voluntary pilot program to examine the possibility of sharing clinical study reports, but it stalled as companies didn’t respond to the agency’s requests for participation. Last year, FDA stopped the program, saying it would seek to harmonize such efforts at transparency with regulatory bodies in other countries.

At the time, FDA said such harmonization could include a centralized international library managed by an independent organization. The agency added that participation would be voluntary.

Read the full BMC Medicine report here: https://bit.ly/3uK54LD.