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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

Authors Response

Our team is appreciative of all the thoughtful discussion this study has generated. We can offer a few remarks.

Dr. Ernst’s raises the issue of “social desirability” as a possible contributor to a placebo response. Indeed, we believe that this could a factor in the placebo response. Dr. Bracken argues that our “augmented” medical encounter is closest to an ‘art” form and involves interpretations of meaning not reducible to empirical study. We disagree and believe that it is essential “to be specific about non- specifics.”

In terms of both of these points, we performed a nested series of in-depth interviews with an additional 27 patients which we expect will provide data to address Dr. Ernst’s question on how patients bonded with researcher and with Dr. Braken’s concern with non-reducible questions of meanings. Dr. Heyland points out that our “augmented” arm may represent a form of psychodynamic-interpersonal therapy. To the extent it does represent this (or as Dr. van Duppen suggests a form of cognitive behavioral therapy), we would say that such a therapeutic relationship might be a valuable component of any positive healing encounter. Actually, we are not sure if it is right or not to consider the patient-physician relationship a part of the placebo effect (endless debates have not resolved this), but it is certainly a “non-specific” component of medical care. Our study suggests that such a supportive relationship can significantly modify the placebo response and contribute towards enhanced clinical outcomes.

We agree with Dr. Pearce that our “limited” arm was unreal and may have exaggerated the benefits of the “augmented” arm. But randomized trials often need to create somewhat unrealistic conditions (e.g., patient populations without co-morbidity) to demonstrate an effect. Also, it should be noted that our study was not designed to compare “limited” with “augmented” but rather determine whether three different non-specific effects could produce outcomes analogous to “dose-dependent.”

Both Dr. Thompson’s comments that a positive therapeutic relationship can engender a strong placebo effect and that physician need more face-to-face time with patients and Dr. Panasoff’s remarks that “physicians are placebo” and are helpful in the context of this entire discussion on whether our patient-practitioner relationship should or should not be considered a placebo effect. Whether our outcomes represent classical conditioning (Pearce) or expectancy (Heyland and Graz) or some combination of both is still unclear to many of our team and needs further study.

We appreciate Dr. Yun’s remarks on acupuncture. But from our perspective, our study has nothing to do with acupuncture. In order to study placebo effects, we used non-penetrating sham needles that scratched randomly selected non-acupuncture points. To our knowledge, mild scratching the skin for six or twelve sessions is unlikely to have any specific effects on digestion. However, the results of our sub-study comparing acupuncture to sham acupuncture will be reported elsewhere.

We agree with Dr. Julyan’s remarks that another arm of just patient-practitioner relationship would have been helpful. His remarks remind us that much work is required before we have a full and comprehensive understanding of placebo effects.

Sincerely,

Ted Kaptchuk
Harvard Medical School Boston, Massachusetts 02215

Competing interests: None declared

Competing interests: No competing interests

04 June 2008
Ted J Kaptchuk
Associate Professor
Harvard Medical School, Boston, MA 02215