Clarification on the ethical use of placebo-controlled trials was published today by the World Medical Association following its four-day Council meeting in Ferney-Voltaire, France.

The WMA's Declaration of Helsinki, acknowledged worldwide as the cornerstone of research ethics, was revised last year and caused some problems with its interpretation. The new guideline calls for the prudent use of placebo in research trials, advising that placebo should only be used in cases where there was no proven therapy for the condition under investigation.

However, at its Council meeting the WMA agreed there were circumstances where a trial might be ethically acceptable even if proven therapy was available. The meeting confirmed these circumstances in a formal note of clarification.

These were:

where for compelling and scientifically sound methodological reasons its use was necessary to determine the efficacy or safety of a prophylactic, diagnostic or therapeutic method; or where a prophylactic, diagnostic or therapeutic method was being investigated for a minor condition and the patients who received placebo would not be subject to any additional risk of serious or irreversible harm.

Commenting on today's clarification, Dr Delon Human, secretary general of the WMA, said:

"We are delighted to have received such a positive endorsement of this important document. With this note of clarification we hope to address any problems with the interpretation of the placebo guideline."

"Our main aim has always been to ensure sound and ethical research as outlined in the Declaration of Helsinki. We believe that a balance between risk and benefit is possible in research."