Intended for healthcare professionals


A meta-analysis of the association between adherence to drug therapy and mortality

BMJ 2006; 333 doi: (Published 29 June 2006) Cite this as: BMJ 2006;333:15

Is the placebo effect always in the right direction?

The authors are to be congratulated on their wide ranging review and
their interesting discussion which was enhanced by the commentary of Betty
Chewning. As observed difference is similar in the active, (specific
effect plus placebo),and the placebo groups the difference must be in the
placebo response, but there may be alternatives to suggestion that this
reflects a generally healthy lifestyle. The placebo reponse is generally
asssumed to be positive. This is almost certainly always true when the
patient comes to the doctor with symptomatic disease.

However there is
possibility that that it is much weakened, or even adverse when the roles
are reversed and the doctor comes to the patient and suggests primary
prevention or treatment of asymptomatic disorders. This has been called
the commoveamus effect in a recent informal article in Clinical Medicine (
Coegemus. Everyone a patient? Beware the Commoveamus effect! Clinical
Medicine 2006 5 665:666). It may be that the poor compliers are those
whose healthy state,which is not the simple antithesis of diseaese, is
critically dependent on the belief that disease is absent and that the
intervention has destroyed this perception, and so their good health. If
so the difference betweeen the two groups should be greater the less the
intervention is related to symptomatic disease. If the hypothesis has any
basis then it has important implications for selection of subjects for
such interventions This might be particularly relevant to those who have
rarely if ever previously attended ther doctor.

Competing interests:
None declared

Competing interests: No competing interests

13 July 2006
CK Connolly
retired physician
Aldbrough St John, Richmond, North Yorkshire DL11 7TP