Intended for healthcare professionals


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

BMJ 2008; 336 doi: (Published 01 May 2008) Cite this as: BMJ 2008;336:999

Placebo needle

We congratulate Kaptchuk et al. (1) on their outstanding report, which was written with considerable ingenuity. Using single-blind placebo acupuncture needles, Kaptchuk et al. assessed three components of placebo effects: assessment and observation, a therapeutic ritual (placebo treatment), and a supportive patient-practitioner relationship. The conclusion that the patient-practitioner relationship is the strongest component is very insightful for evaluating the benefit of complementary and alternative medicine. They treated patients with irritable bowel syndrome, who were allotted to the following treatment groups: waiting list, placebo acupuncture alone (limited) and placebo acupuncture with a defined positive patient-practitioner relationship (augmented). In this report, the patients were well masked, i.e. 76%-84% and 56%-84% of the patients believed that they received genuine acupuncture at 3 and 6 weeks of treatment, respectively. This implies that a large proportion of the patients perceived specific sensations associated with skin pressure during blunt tip needle application, making them believe that the treatment received was genuine.

We believe that the sensations elicited by the placebo or real needle had significant psycho-physiological impact on the patients in terms of therapy. Since the practitioners were well trained to adhere to the protocol throughout the experiment, there might be no significant difference in the sensations during placebo application between limited and augmented treatments. However, if this is not the case, the role of psycho-physiological impact by placebo application cannot be excluded in bringing about a greater improvement in the augmented group compared to the limited group. For the single-blind needle used in this study, the amount of skin pressure by the blunt tip could not be controlled mechanically or automatically and was dependent on the unmasked practitioner's discretion, which might have led to a possible bias. We believe that the skin pressure should be kept equal throughout the experiment, and if the patient-practitioner masking placebo needle is used (2), the practitioner bias is no longer a cause for concern.

(1) Kaptchuk TJ, Kelley JM, Conboy LA, Davis RB, Kerr CE, Jacobson EE et al. Components of placebo effect: randomised controlled trial in patients with irritable bowel syndrome. BMJ 2008; doi:10.1136/bmj.39524.439618.25:1�E.

(2) Takakura N, Yajima H. A double-blind placebo needle for acupuncture research. BMC Complement Altern Med 2007;7:31.

Competing interests: None declared

Competing interests: No competing interests

05 June 2008
Nobuari Takakura
Research Manager
Hiroyoshi Yajima
Hanada College, 20-1 Sakuragaoka-machi Shibuya-ku Tokyo 150-0031