Uncomfortable implications: placebo equivalence in drug management of a functional illness
- Professor H M Evans, Centre for Arts and Humanities in Health and Medicine, Durham University, School House, St Hild's Lane, Durham DH1 1SZ, UK; h.m.evans{at}durham.ac.uk
- Received 26 October 2006
- Revised 15 January 2007
- Accepted 31 January 2007
Abstract
Using a fictional but representative general practice consultation, involving the diagnosis of irritable bowel syndrome in a patient who is anxious for some relief from the discomfort his condition entails, this paper argues that when both (a) a drug fails to out-perform placebo and (b) the condition in question is a functional illness with no demonstrable underlying pathology, then the action of the drug is not only no better than placebo, and it is also no different from it either. The paper also argues that, in the circumstances of the consultation described, it is striking that current governance deems it ethical for a practitioner to prescribe either a drug or a placebo, both of which appear to rely for their effectiveness on a measure of concealment on the part of the doctor, yet deems it unethical for a practitioner openly to prescribe a harmless and enjoyable substance which (in equivalent conditions of transparency and information) is likely to be no less effective than either drug or placebo and is also likely to be better-tolerated and cheaper than the drug.
Footnotes
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↵i When both are blinded. We are unaware of any trials comparing them when both are unblinded as we define that term here in relation to SAS and placebo. Such a trial would compare an open-label placebo with open-label SAS, the participants knowing both what preparation they were receiving and also the fact of the placebo-equivalence of SAS, which was presumably not known to the participants in the original trial. An alternative suggestion, which we owe to Dr Michael King, would be for an open-label placebo to be trialled against an open-label drug acknowledged as being only problematically relevant (cf trials of various cardioactive drugs thought to have therapeutic potential for the management of Alzheimer disease, for example).
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↵ii We are grateful to Dr Martin Schlup for this point.
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↵iii We accept that a drawback of placebo controlled trials is their inability to distinguish between individual patients who might have benefited from the intervention—that is, real people, rather than “statistical people” who might have experienced an effect somewhere in the trial population. However, our interpretation of trials is based on the overall interpretation of results; an “effect” calculated overall to be around that of placebo is not interpreted positively. Clinical practice eschews the use of interventions with such results in the absence of other reasons to think the intervention worthwhile in an individual case. Basing clinical practice on a chance, literally, that the patient will receive benefit greater than placebo defies the tenets of evidence based practice, particularly as active drugs frequently have side effects. It may be that certain subgroups of patients could be identified who might have unequivocal benefits from the intervention, but establishing this would require new trials.
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↵iv If eaten and enjoyed as intended, Swotties cannot be blinded. Blinding them—for instance, by requiring that they be swallowed whole rather than chewed—entails losing their advantage in palatability, but their other advantages remain.
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Competing interests: HME: None declared. APSH has served on the Advisory Board of companies manufacturing products for functional bowel diseases and has received research and conference grants from such sources.
- Abbreviations:
- IBS
- irritable bowel syndrome
- SAS
- [hypothetical] specific antispasmodic
