As the debate about publishing raw data from trials continues to heat up, some 53 participants from clinical studies have written to the European Medicines Agency claiming that the lack of regulations requiring full publication is "a betrayal of our trust".

The letter, addressed to EMA executive director Guido Rasi, notes that the participants, some healthy and some with medical conditions. all agreed to take part in studies "in the belief that we were helping to improve knowledge and treatments. We now understand that many participants in trials have been misled".

They argue that "about half of all clinical trials have not been published and that this proportion has seen only a small improvement over the past few years. Furthermore, both companies and independent researchers can withhold information about clinical trials from doctors and researchers even when asked for it" .

This means "that the findings generated from our participation and that of thousands of others in the trials may not be available to the doctors, researchers and regulators who work on particular diseases or make decisions about their treatments", the letter continues.  It also means some of the trials could be repeated in the future, when they do not need to be.

The participants say that "this is dangerous and expensive and it holds back good medicine". Furthermore, "it is also a betrayal of our trust in clinical trial regulation, and the trust of the families of those patients who volunteer for trials having had a terminal diagnosis".

The letter concludes by asking Dr Rasi "to put in place measures to ensure that the protocols for all clinical trials from now on - and all clinical trials since the 1980s – are posted on a public register". The participants also demand that "the summary results, the 'primary and secondary outcomes' measured in all these trials and the clinical study reports are published".

The letter comes as the AllTrials campaign led by Bad Science, Sense About Science, the BMJ, James Lind Initiative and Centre for Evidence-based Medicine continues apace. Also this week, in the UK, the House of Commons Health Select Committee report on the National Institute for Health and Clinical Excellence spoke of "both a professional and legal obligation to ensure that all regulators, including NICE, have access to all the available research data about the efficacy and safety of pharmaceutical products”. The report added that “we do not believe it should be either legal or considered ethical to withhold research data".