40% of Drug Studies Required After Approval Are Missing Key Data in EU Registry
When a medicine receives regulatory approval, the scientific evaluation does not end. Post-authorization studies - designed to collect real-world data on safety and effectiveness after approval - are a standard condition of market entry for many drugs. The European Medicines Agency maintains a public catalogue of these studies. Researchers at the BMJ have now systematically examined how many of those studies are actually making their data publicly available.
The answer is: many are not. An analysis published in The BMJ found that only 59.6 percent of ongoing and finalized post-authorization studies in the EMA catalogue had uploaded a protocol. Among finalized studies - those that have concluded and should have results to share - only 68.4 percent had uploaded results.
What the rules say and what happens in practice
EU legislation requires that protocols and results for Category 1 and 2 studies in an EU Risk Management Plan be uploaded to the EMA catalogue. For other study categories - including EU RMP Category 3 studies, non-EU RMP studies, and studies not included in any RMP - the EMA issues recommendations rather than legal requirements. The compliance gap is visible across both mandatory and recommended categories, but it is largest in the categories where only recommendations, not legal obligations, apply.
Among finalized Category 1 studies, 90 percent had uploaded results - the highest compliance rate in the analysis. Among finalized studies not included in any RMP, only 64 percent had results available. Protocols tell researchers and regulators what a study is designed to measure; results tell them what it found. Both are necessary for meaningful scientific oversight of post-approval drug safety.
Why this matters for scientific review
Post-authorization studies exist because pre-approval trials cannot capture everything relevant about a drug's safety and effectiveness. Trial populations are carefully selected; real-world patients have comorbidities, take other medications, and use drugs in ways that trials cannot fully anticipate. Post-authorization studies are meant to detect safety signals and effectiveness patterns that only emerge at scale and over time.
If those studies do not make their protocols and results publicly available, the scientific community cannot evaluate whether they were conducted appropriately, whether they found safety signals, or whether the methods used were adequate to detect the outcomes they were designed to assess. Sponsors can define the scope of a study, complete it quietly, and satisfy their obligation to register it - without meaningful transparency about what it found.
What the data cannot tell us
The analysis is a snapshot drawn from the EMA catalogue in February 2024. It captures the upload status at a single point in time and relies on the accuracy and timeliness of metadata entered by study sponsors. Studies may have uploaded data after the analysis date, or may have legitimate reasons for delayed posting that the catalogue data does not capture. Adherence varied considerably across sponsors - a pattern that the authors note but that the study's aggregate approach cannot fully characterize.
The authors describe their conclusion simply: "Better adherence is needed for greater research transparency." The gap between legal requirements and actual compliance, and between recommendations and behavior, represents a structural weakness in the post-market surveillance system that underpins drug safety monitoring across the EU.