The context and meaning of placebos for complementary medicine

Calls for placebo-controlled randomised trials in complementary and alternative medicine (CAM) are entirely reasonable. However, they present major methodological problems, particularly when we understand so little about the underlying biological mechanisms involved for many of these therapies. Designing a placebo in CAM is frequently dependent on unsubstantiated assumptions about the specificity of a particular CAM intervention. In this paper we address the development and application of placebos to clinical trials of homeopathy, acupuncture, kinesiology, Chinese herbal medicine and healing. Each therapy-based vignette is authored by a researcher from the Complementary and Integrated Medicine Research Unit at the University of Southampton who has specific expertise in the field. The essential research question within this review is; can we legitimately claim to have placebos for these particular CAM interventions? In some areas of CAM the debate has become very involved and sophisticated, for instance in acupuncture but for other areas, such as healing, our understanding of placebos is currently limited and very naïve. For instance, if acupuncture is not point specific, then many so-called 'placebo-controlled' acupuncture trials are both misconceived and misleading. We have addressed this debate in what we hope is a thoughtful and rigorous manner with a view to developing realistic, reliable and credible placebos for randomised controlled studies when and where possible. However, our conclusions suggest that we are some way from developing valid, credible and reliable placebos for most CAM therapies.