Intended for healthcare professionals

Research

Components of placebo effect: randomised controlled trial in patients with irritable bowel syndrome

BMJ 2008; 336 doi: https://doi.org/10.1136/bmj.39524.439618.25 (Published 01 May 2008) Cite this as: BMJ 2008;336:999

Which are the placebo effects - comment on Kaptchuk et al’s IBS placebo study

“A placebo can only be assumed to be inert according to current knowledge” [1]. The sham procedure used in Kaptchuk et al’s IBS placebo study [2] is already known not to be inert. One cannot touch the body without biological effects. Some of these effects may in theory be attributable to placebo, others are normal reactions to touch and can have many dimensions to them [3, 4]. Therefore the sham acupuncture which necessarily involves touch and pressure is not an inert placebo (something admitted by its proponents [5]) and cannot have effects solely attributable to the ritual of therapy [6] as the authors claim [7]. Thus placebo effects in both the sham treatment arms are necessarily overstated. Additionally some aspects of the effects of touch are probably specific to the acupuncture therapy [8], a possibility acknowledged by the lead author in recent discussions about the role of touch in taiji chuan [9, 10].

In these articles about taiji chuan the lead author also demonstrates knowledge of complex interventions and the difficulties of doing research on them. Among other things, the evidence he cites comes from acupuncture related studies showing how many aspects of patient-practitioner psycho- social-verbal interactions are specific aspects of acupuncture treatment [11]. This and other supporting studies have demonstrated the complex nature of acupuncture as an intervention [8, 12]. Unfortunately in the third arm of the IBS placebo study since sham acupuncture was used to investigate placebo effects, not only is there a problem with the sham not being inert, but the study will have attributed to placebo some effects due to these non-placebo related specific components of acupuncture intervention. There is no discussion of this and no attempt to tease apart placebo related treatment components from these acupuncture specific non- placebo related patient-practitioner interactional components [12]. Thus the study will necessarily have further overestimated placebo effects in this third arm, due to this mislabeling of treatment components.

This placebo study chose to use sham acupuncture as its ‘placebo’ treatment. This was an unfortunate choice. No sham acupuncture treatment has ever been demonstrated to be inert, raising questions about bias in acupuncture studies [1] and thus the suitability of sham acupuncture in trials of acupuncture [13]. Recently experts have raised the issue of whether there should be a moratorium on sham acupuncture studies due in part to these difficulties [14]. The authors of this study have chosen to ignore the same evidence and arguments about complex interventions and the inherent difficulty of separating their placebo effects that they have used and cited elsewhere [8, 9, 10], raising other questions about this placebo study.

It would have been much more interesting and relevant to answer the questions about placebo that this study attempted to investigate if they had chosen a sham (placebo) standard pharmaceutical intervention administered in normal GP practice where the doctor usually does not have time to talk much with the patient, and use as a third arm an extended discussion treatment arm added to the placebo medication.

References

1. De Craen AJM, Tijssen JGM, Kleijnen J. Is there a need to control the placebo in placebo controlled trials? Heart. 1997;77:95–96.

2. Kaptchuk TJ, Kelley JM, Conboy LA, Davis RB, Kerr CE, Jacobson EE, Kirsch I, Schnyer RN, Nam BH, Nguyen LT, Park M, Rivers AL, McManus C, Kokkotou E, Drossman DA, Goldman P, Lembo AJ. Components of placebo effect: randomized controlled trial in patients with irritable bowel syndrome. BMJ, 2008:336(7651):999-1003.

3. Fields T. Touch Therapy. London, Churchill Livingstone. 2000.

4. Leder D, Krucoff MW. The touch that heals: the uses and meanings of touch in the clinical encounter. J Alt Complem Med. 2008:14(3):321-327.

5. White AR. Acupuncture research methodology. In Lewith G, Jonas WB, Walach H, eds. Clinical Research in Complementary Therapies. Edinburgh: Churchill Livingstone, 2002:307–323.

6. Birch S. Comment on 'sham device v inert pill: randomised controlled trial of two placebo treatments. February 9, 2006 & Yes let’s get real: what placebo isn’t. March 10, 2006. http://www.bmj.com/cgi/eletters/332/7538/391#129658

7. Kaptchuk TJ, Stason WB, Davis RB, Legedza ART, Schnyer RN, Kerr CE, Stone DA, Nam BH, Kirsch I, Goldman RH. Sham device v inert pill: randomized controlled trial of two placebo treatments. BMJ 2006; 332:391- 397.

8. Schnyer R, Birch S, MacPherson H. Acupuncture practice as the foundation for clinical evaluation. In MacPherson H, Hammerschlag.R, Lewith G, Schnyer R (eds). Acupuncture Research: Strategies for Building an Evidence Base. London, Elsevier, 2007:153-179.

9. Wayne PM, Kaptchuk TJ. Challenges inherent in T’ai Chi research: Part I - t’ai chi as a complex multicomponent intervention. J Alt Complem Med. 2008:14(1):95-102.

10. Wayne PM, Kaptchuk TJ. Challenges inherent in T’ai Chi research: Part II - defining the intervention and optimal study design. J Alt Complem Med. 2008:14(2):191-197.

11. Paterson C, Dieppe P. Characteristic and incidental (placebo) effects in complex interventions such as acupuncture. BMJ, 2005:330:1202- 1205.

12. MacPherson H., Thorpe L, Thomas K. Beyond needling - therapeutic processes in acupuncture care: a qualitative study nested within a low back pain trial. J Alt Complem Med, 2006:12(9):883-880.

13. Birch S. A review and analysis of placebo treatments, placebo effects and placebo controls in trials of medical procedures when sham is not inert. J Alt Complem Med, 2006: 12(3):303-310.

14. Paterson C. The colonization of the lifeworld of acupuncture: The SAR conference. J Alt Complem Med. 2008:14(2):105-106.

Stephen Birch Foundation (Stichting) for the Study of Traditional East Asian Medicine (STEAM), Amsterdam, the Netherlands

Mark Bovey Coordinator, Acupuncture Research Resource Centre, Thames Valley University, London, UK

Competing interests: None declared

Competing interests: No competing interests

30 June 2008
Stephen Birch
Acupuncture practice, education and research
Mark Bovey
Amsterdam, 1054SG