European Clinical Trial Registry Shows Low Results Reporting Rates

An analysis of a key European clinical trial database found that results were reported within the required time frame for fewer than half of the registered studies. Complete results were fully reported for only 42 percent of the studies. The analysis examined 234 clinical trials for which results were supposed to have been disclosed.

More than 99 percent of expected data was found in those trials. Researchers concluded that overall compliance with legal reporting requirements was weak and that regulatory oversight is lacking. European Union and member state regulators “have so far not delivered the promised ‘high levels of transparency never seen before for clinical trials,’” the authors wrote.

The analysis was posted on the medRxiv preprint server. It has not yet been peer-reviewed. The article was published on June 15, 2026.