Reply to Edzard Ernst and Peter Canter

Thank you for the opportunity to respond to the letter from Professor Ernst and Dr Canter. Their letter was a welcome contribution to the debate about appropriate methodologies for researching homeopathy and complementary medicines in general.

We agree with the principle that hypotheses, such as the one we suggest, of an interaction between specific and non-specific effects, should be tested. Nevertheless, because there is a possibility this interaction does exist, we consider it wise to adopt the precautionary principle in the design of trials. The precautionary principle, if applied to placebo-controlled RCTs of homeopathy, could determine that although this interaction has not been unequivocally demonstrated, there remains a significant risk of it occurring and this could make a contribution to the difference between treatment and placebo arms. This contribution is not measurable within a standard RCT and has the potential to distort results from such trials. Until we have a model that can measure such interaction effects, we should approach placebo RCTs of homeopathy with the caution that we recommend in our paper.[ ¹ ]

Ernst and Canter suggest a test of whether in fact there is an interaction between specific and non-specific factors by using a design in which there is a ‘minimal consultation’. It is conceivable to us as practising homeopaths that a shortened consultation in which the ‘bare bones’ of information required to decide on a prescription could be conducted in some cases. However in chronic conditions (which are the majority of problems presented to homeopaths[ ² ]) it is hard to see how a genuine homeopathic consultation could be conducted without enquiring into the aetiology of the condition and the patient's general, emotional and mental symptoms. Inevitably in such cases, even a ‘minimal consultation’ would entail some degree of psychodynamic relationship. In fact, it is probable that even any brief meeting of one person with another in the context of health care has the potential for the participants to experience some ‘meaning’ from this.[ ³ ] Thus, we are not confident that a ‘minimal consultation’ could be equivalent to eliminating the non-specific effects of the consultation.

Ernst and Canter's suggestions for testing whether the uncertainty experienced by homeopaths in placebo-controlled RCTs is different in treatment and placebo arms are interesting and we think that they would provide a good test of this. Our only reservation is the proposal not to inform homeopaths of the possibility that patients will receive placebo. In various research communities, there has been considerable debate about the ethics of deception. For example, in 2000, the Ethics Committee of the British Psychological Society debated the issue of deception in experimental research and it concluded that:

...the central principle was the reaction of participants when deception was revealed. If this led to discomfort, anger or objections from the participants then the deception was inappropriate.’[ ⁴ ] (page 6)

It is likely that homeopaths would be uncomfortable with and angry about being deceived that their patients had received placebo within a trial. Whilst not all medical researchers are bound by this code of conduct, it is ethically highly dubious, and it is likely that research ethics committees would take a dim view of the intention to deceive practitioners. Further, we consider that research study participants (both practitioners and patients) would be unhappy if the process of providing evidence relevant to users and purchasers of healthcare became so abstract that the research process began to look like an elaborate game.

Returning to our original comments that randomised double-blind placebo-controlled trials are not always the most appropriate way to answer questions about the effectiveness of complex interventions such as individualised homeopathy, we might be better as a community to focus our energies on questions that can more easily be asked and that relate directly to helping those in the struggle to deal with difficult and disabling chronic conditions.

• References

• 1 Weatherley-Jones E, Thompson E.A, Thomas K.J. The placebo-controlled trial as a test of complementary and alternative medicine. observations from research experience of individualized homeopathic treatment. Homeopathy 2004; 93 (04) 186-189.
• 2 Vincent C, Furnham A. Why do patients turn to complementary medicine? An empirical study. Br J Clin Psychol 1996; 35: 37-48.
• 3 Moerman D.E, Jonas W.B. Deconstructing the placebo effect and finding the meaning response. Ann Intern Med 2002; 136: 471-476.
• 4 http://www.bps.org.uk/documents/Code.pdf accessed 5th November 2004.