European non-commercial sponsors showed substantial variation in results reporting to the EU trial registry

Objective: To describe the trial results reporting behavior of leading European non-commercial sponsors by country and over time. Study design and setting: Cross-sectional analysis describing results reporting rates to the European Clinical Trials Registry among the top sponsors across Europe as of May 2021 and a comparison of reporting trends for a cohort of major sponsors between January 2018 and May 2021. Results: Fifty-nine highly active sponsors from 10 countries and 9 collaborative groups had 1,916 trials due to report, representing 14% of all due trials on the registry (n = 13,709); of these, 1,058 had reported results (55.2%). Sponsors in the UK, Belgium and Germany had the highest compliance at 94%, 69% and 58%; those in Spain, France and the Netherlands, had the lowest, ranging from 4% to 21%. Collaborative groups had a reporting rate of 50%. In the major sponsors cohort (n = 49), those with no reporting to the registry decreased from 27 (55%) in 2018 to 10 (20%) in 2021. Thirteen of these sponsors (27%) reached a 90-100% reporting rate in 2021 compared to 0 in 2018. Conclusion: Compliance with EU regulations by non-commercial sponsors is highly variable between countries. Enforcement of EU reporting regulations should be prioritized.