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

Doctor-patient interaction is not an element of the placebo effect

Kaptchuk et al[1] make a stimulating contribution to our thinking about the effective elements of medical treatment in their study of patient response to three so-called placebo conditions – waiting list observation, sham acupuncture, and sham acupuncture plus practitioner interaction – for irritable bowel syndrome (IBS). We were not surprised to see that patients in the third arm of their study (those receiving ‘augmented interaction’) showed clinically significant improvements in several IBS-related domains. Why were we not surprised? First, because this ‘placebo’ condition permitted many of the non-specific factors of psychotherapy that are widely understood to be efficacious[2]. A closely related concept - the therapeutic alliance - has been consistently shown to be positively associated with clinical outcome, even for pharmacotherapy studies[3].

Second, although the authors attempted to control for psychotherapeutic factors by not allowing ‘specific cognitive and behavioural interventions that might be beneficial for irritable bowel syndrome’ in the ‘augmented interaction’ condition, they unfortunately made no reference to another form of evidence-based psychotherapy for IBS. Two substantial randomised controlled trials[4,5] have shown the effectiveness of psychodynamic-interpersonal (PI) therapy for IBS. This is a significant omission from the paper by Kaptchuk et al, as it means that PI interventions were not controlled for in the present study. In fact the permitted clinician behaviours in the augmented interaction group seem at face value to map closely onto interventions expected in PI therapy (eg exploring the patient’s causal attribution of their IBS, making links between IBS and relationships). It seems the authors were offering some of their subjects PI therapy without knowing it.

On a more general note, we would argue strongly that it is incorrect to label ‘patient-practitioner interaction’ as an element of the placebo effect at all. The term ‘placebo’ means that the treatment is inert, that it contains no active ingredient. Any resulting treatment effect is therefore due to expectancy on the part of the patient. This expectancy effect is what should be labelled placebo. Therefore to lump the patient- practitioner interaction in with expectancy effects and call them both placebo is wrong. In fact patient-practitioner interaction is the primary active ingredient of most if not all psychological treatment, whether for IBS or any other disorder, with or without a ‘therapeutic ritual’, as practised by general physician or specialist psychotherapist. The quality of this relationship has been shown to account for 30% of outcome variance, compared to just 15% for expectancy/placebo[6].

Simon Heyland, Specialist Registrar in Psychotherapy
Jim Moorey, Consultant Clinical Psychologist
Gaskell House Psychotherapy Service, Manchester M13 0EU

Competing interests: JM trains and supervises clinicians practising psychodynamic-interpersonal therapy.

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; 336: 999-1003.

2. Frank JD & Frank JB. Persuasion & Healing: a comparative study of psychotherapy. Baltimore: John Hopkins University Press, 1991.

3. Elkin I, Shea MT, Watkins JT, Imber SD, Sotsky SM, Collins JF et al NIMH Treatment of Depression Collaborative Research Program: general effectiveness of treatments. Arch Gen Psych 1989;46:971-82.

4. Creed FH, Fernandez L, Guthrie E, Palmer S, Ratcliffe J, Read N, et al. The cost-effectiveness of psychotherapy and paroxetine for severe irritable bowel syndrome. Gastroenterology 2003;124:303-17.

5. Guthrie E, Creed, Dawson D and Tomenson B. A controlled trial of psychological treatment for the irritable bowel syndrome. Gastroenterology 1991;100:450-57.

6. Lambert MJ. Psychotherapy outcome research: implications for integrative and eclectic therapists in Norcross JC and Goldfried MR (eds) Handbook of Psychotherapy Integration. New York: Basic Books, 1992.

Competing interests: JM trains and supervises clinicians practising psychodynamic-interpersonal therapy.

Competing interests: No competing interests

14 May 2008
Simon J Heyland
specialist registrar in psychotherapy
Jim Moorey
Gaskell House Psychotherapy Centre, Swinton Grove, Manchester M13 0EU