Sham procedures and the ethics of clinical trials.

Placebo-controlled trials of pharmacological treatments are typically conducted double-blind—that is, neither the patients nor the investigators know whether the substance administered is the agent under investigation or placebo. The process of masking treatment assignment is generally considered ethically acceptable provided that the ‘shared ignorance’1 has been made clear in the consent process. However, in circumstances where a surgical or medical procedure itself constitutes the treatment, a randomized placebo-controlled trial raises different issues. Here only the patient-subject is kept in ignorance, and the clinician, who can distinguish active from inactive treatment, may be required to engage in active deception. Examples are surgical operations, acupuncture and specific methods of psychotherapy. Recent papers on the ethics of such trials have focused on the risk–benefit assessment of invasive sham interventions.2–11 Little attention has been given to the psychological and ethical concerns generated by the need for deliberate deception.