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 or nocebo?

We congratulate Kaptchuck et al [1] on their important paper. We agree that a therapeutic relationship which engenders a strong placebo effect is the practitioner's most important tool in managing patients whose chronic symptoms have no apparent cause. In primary care, Thomas [2] found that the effectiveness of a doctor visit increased from 39 to 64%, when it included a diagnosis and a positive attitude, with or without a placebo pill. In another study [3], patients with non-cardiac chest pain who obtained reassurance from negative lab tests (though of no diagnostic value) were back to work faster, were more satisfied with care, and sought less help than controls.

In irritable bowel syndrome, we [4] have advocated a firm diagnosis accompanied by explanation and truly effective reassurance, such that lingering fears of serious disease are allayed. Psychosocial circumstances may impair a patient's ability to cope with symptoms, for exmple, an over- busy cell phone-dominated lifestyle can compete with basic biological activities such as eating, sleeping, defecation and even sex. Therapists’ greatest gift to such patients can be time spent exploring with them the implications of their lifestyle on their well-being – empathy in action.

If, in a clinical trial, therapeutic benefit = therapeutic gain from a treatment + disorder's natural history + placebo effect [5]; then, another possibility is: therapeutic loss = therapeutic gain from a treatment + disorder's natural history - nocebo effect.

In the former case, a harmful treatment (such as bloodletting) may achieve a net benefit if it is accompanied by a large placebo effect from the personality and reputation of the practitioner and the mystique of the procedure. In the latter case, a useful treatment such as dietary advice may be undermined by poor doctor/patient interaction. Healthcare systems that assign more value to technological procedures than to consultations and which provide inducements for rapid patient turnover are nocebos in this group of patients. Doctors need face-to-face time to bring to bear their personality, reputation, authority, and reassuring compassion. There is no need for dummy pills; the placebo is the doctor [5].

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

2. Thomas KB, General practice consultations: is there any point in being positive? BMJ 1987; 294:1200-2

3. Sox HCJr, Margulies I, Sox CH. Psychologically mediated effects of diagnostic tests Ann Int Med 1981; 95:680-5

4. Thompson WG, Heaton KW. Irritable Bowel Syndrome, 2nd edn. Health Press, Abingdon, 2003

5. Thompson WG The Placebo Effect in Health and Disease: Combining Science and Compassionate Care. Prometheus Press, Amherst NY, 2006

Competing interests: None declared

Competing interests: No competing interests

13 May 2008
W Grant Thompson
Emeritus professor of medicine, University of Ottawa
Kenneth W. Heaton
7 Nesbitt Street, Nepean, Ontario, K2H 8C4, Canada