How informed is consent in sham-controlled trials of acupuncture?

We sought to investigate whether, and if so, how published sham-controlled trials of acupuncture report on the information given to patients about true and sham interventions. We asked acupuncture therapists to provide original patient information leaflets in order to study how interventions were described in more detail.

Forty-seven (47) published sham-controlled trials of acupuncture collected for a systematic review on sham techniques were screened to determine whether they reported on information given to patients about study interventions; any such information was extracted. We contacted authors of published studies and other researchers in the field and asked them to provide copies of original patient information leaflets. Information given to patients about true and sham interventions was extracted.

Ten (10; 21%) of the 47 published studies included some information on how patients were informed. None of these studies appear to have used the term "sham" or "placebo" and most appear to have suggested that two types of acupuncture were compared. In the 16 original patient information leaflets obtained, the way patients were informed varied greatly: 7 leaflets explicitly included words such as "sham," "placebo," or "dummy." Others described the control intervention as not meeting all criteria of acupuncture. Finally, one group of studies simply suggested that different types of acupuncture were being compared.

Our results indicate that (1) only a minority of published trials report on information given to patients about true and sham interventions and (2) that information strategies vary considerably and are often not fully explicit. This has not only ethical relevance but also might influence results of trials.