Regulatory experience of TOPS: an internet-based system to prevent healthy subjects from over-volunteering for UK clinical trials.

The findings continue to support the concept that TOPS not only helps to prevent over-volunteering, but also deters subjects from trying to do so. Regulation of TOPS by the HRA and MHRA has enhanced its effectiveness, benefited all users and helped to improve the safety of volunteers who participate in non-therapeutic trials in the UK. The UK is still the only country with a national database to prevent over-volunteering that has published data on its widespread use and effectiveness.