Specific effects of homeopathy: The challenge of explanatory research

Development of clinical research in homeopathy faces many challenges. These include meeting the need for more pilot trials and greater focus on medical conditions for which conventional medicines are inadequate or ineffective. Suitable study design for such work must be selected on the basis of a precisely asked research question: an explanatory trial aims to find out whether a particular medicine has any efficacy in treating a highly defined group of patients, and would be placebo-controlled; a pragmatic trial aims to find out the effectiveness of treatment in everyday practice for a particular condition, and would involve comparison with standard medical care or no treatment.[ ¹ ]

The first of those designs can provide information about the specific effects of a medicine, whereas the second informs about the entire ‘package of care’ including specific and non-specific effects. By combining these two distinct designs in a single trial, one could theoretically answer the question: what are the relative contributions of the specific and non-specific effects of homeopathy? A paper published in this issue of the journal has set out to tackle the question in this way.[ ² ] The new research has also embraced the principles of applying a pilot protocol to the investigation of an important but under-researched medical condition (in this case, dermatitis).

Using a 4-group trial method, the authors have sought to discover whether a combined explanatory and pragmatic approach is both viable and capable of informing the statistical evaluation of a larger study. Regrettably, it seems the answer is ‘no’ in both cases. The crucial issue appears to be patient preference. Half the patients were blinded to group allocation, and blinded subjects dropped out of the study more readily than people who were aware of their treatment status. Reasonably, the authors concluded that a full trial of this design would be unlikely to yield sufficient data to address the question of specific and non-specific effects.

We are left to ponder how the question might be answered effectively. It seems unlikely to be solved in a single study. The authors of the paper suggest that their data could inform a 2-group, double blind, placebo-controlled trial of homeopathy for dermatitis. Although the question of interaction between specific and non-specific effects cannot be ignored,[ ² ] a rigorous explanatory trial of this type could focus on the specific effects of a given homeopathic medicine in patients with this condition. To achieve it, the trial should restrict inclusion to those patients whose symptoms match a pre-selected single remedy. Data from the current pilot study suggest that Mixed Pollen 30c, Phosphorus 6c or Sulphur 6c could be the optimum candidates for investigation (because of their high prescribing frequency). The study should certainly extend the treatment period beyond 3 months, as the authors indicate. In addition, it would seem necessary to specify more narrowly the type of dermatitis, perhaps restricting assessment to the atopic condition only. Of course, the challenge would be to recruit sufficient numbers of patients who fulfil all these criteria; a multi-centre approach would be the obvious solution.

It would be a precise and important step forward in developing our knowledge of homeopathic medicine, and positive findings would lead to further targeted research. Separate investigation of dermatitis using pragmatic design would give insight into the overall effectiveness of homeopathic treatment in this condition. Any temptation to study unrestricted individualised therapy using placebo-controlled design is probably best resisted until more is understood about how to interpret the findings of such trials, for studies of this type do not satisfy the normal requirements of explanatory research.[ ^3,4 ] It is another of the key challenges facing clinical research development in homeopathy.

• References:

• 1 MacPherson H. Pragmatic clinical trials. Complement Ther Med 2004; 12: 136-140.
• 2 Fisher P., McCarney R., Hasford C., Vickers A. Evaluation of specific and non-specific effects in homeopathy: Feasibility study for a randomised trial. Homeopathy 2006; 95: 215-222.
• 3 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 individualised homeopathic treatment. Homeopathy 2004; 93: 186-189.
• 4 Paterson C., Dieppe P. Characteristic and incidental (placebo) effects in complex interventions such as acupuncture. Br Med J 2005; 330: 1202-1205.