Our analysis suggests that the treatment factors that are characteristic of acupuncture include, in addition to the needling, the diagnostic process and aspects of talking and listening. Within the treatment sessions these characteristic factors are distinct but not divisible from incidental elements, such as empathy and focused attention. These findings have important consequences for the design of trials. A sham controlled acupuncture trial, the classic design for efficacy or explanatory trials, is based on the supposition that the needling alone is the characteristic treatment element. Therefore participants in the control group receive everything except the needling. If, however, other aspects of treatment are characteristic, the sham acupuncture design is inappropriate because it delivers these other characteristic elements to both groups. Consequently, the difference between the groups may greatly underestimate the total treatment effect of the intervention ().
Application of randomised controlled design to trial of non-pharmaceutical intervention such as acupuncture
A sham controlled trial is only appropriate for comparing two acupuncture interventions—for example, to compare the effects of different needling techniques. In such a trial it is the effect of needling that is being compared rather than the total characteristic effect of the acupuncture.
Many thoughtful papers about trial design in complementary medicine have aired similar concerns.9,13,15,16
For example, members of the International Acupuncture Research Forum acknowledged that “Some effects that are included in the term `non-specific' may be peculiar to acupuncture,”17
and a scholarly overview of controlled clinical trials in acupuncture recognised: “The probable interaction of treatment effects of the different specific and non-specific effects of the treatment.”18
Nevertheless, these papers have continued to recommend using sham controlled acupuncture studies. This reticence in challenging the status quo may be because the assumptions that underlie dominant or commonly held theories such as biomedicine are invisible until they are illuminated by a body of primary research.
Our findings may also prove useful in understanding some of the many paradoxes within the literature on the placebo effect. For example, they explain two recurring paradoxes in relation to sham acupuncture trials. Firstly, the discrepancy between acupuncture's long history and widespread use and its lack of proved clinical effectiveness in randomised controlled trials and, secondly, the fact that generally both sham and real acupuncture have good treatment effects.9