Evidence Check 2: Homeopathy - Science and Technology Committee Contents

Memorandum submitted by Dr Clare Relton (HO 32)


  1.  This submission proposes that there is clarity in the key terms used in the inquiry: "homeopathy" and "evidence base".

  2.  "Homeopathy" is a term with multiple meanings which include:

    (a) Therapeutic system of homeopathy

    (b) Homeopathic products/medicines/remedies/pillules

    (c) Homeopathic services/treatment by a homeopath

    (d) Principles of homeopathy:

(i) Principle of Similars ("like cures like")

(ii) Principle of Minimum Dose

  3.  If understanding in this area is to progress, then the precise meaning of the term "Homeopathy" (a, b, c or d), should be stated.

  4.  Evidence base: there are many different types of evidence. We must be clear as to the nature of a) the evidence called for, b) the evidence cited and c) the evidence that exists.

  5.  The type of evidence called for to address a question, should match the evidence that is required to address that question, ie does this question require evidence of efficacy, clinical effectiveness, cost effectiveness, acceptability, safety..?

  6.  Thus each question in this inquiry will require clarification as to:

    (a) What aspect of "homeopathy" is being referred to in this question (a,b,c,di,dii)?

    (b) What type of evidence is required to answer this question?

    (c) Whether the quality and the quantity of the existing evidence is sufficient evidence to yield an answer?

    (d) If not, then can this evidence be produced?


  7.  Medical Subject Headings (MeSH) Terms were developed by the United States National Library of Medicine in order to index articles in Index Medicus and MEDLINE in order to provide a standardised way to describe diseases, symptoms, treatments, drugs etc. http://www.nlm.nih.gov/cgi/mesh/2007/MB_cgi

  8.  The MeSH term for "Homeopathy"describes it as: "A system of therapeutics founded by Samuel Hahnemann (1755-1843), based on the Law of Similars where "like cures like". Diseases are treated by highly diluted substances that cause, in healthy persons, symptoms like those of the disease to be treated. The dilutions are repeated so many times that there is less than one molecule per dose and it is suggested that benefit is from the energetic life force of the original substance." (National Library of Medicine, 2007). The term "homeopathy" here is used to refer to:

    (a) the "system of therapeutics"—Therapeutic System

    (b) doses—homeopathic products, medicine, pillules.

in addition to these meanings, the term "homeopathy" is also used to refer to:

    (c) Homeopathic services/treatment by a homeopath

    (d) One or more of the Principles of homeopathy:

(i) Principle of Similars ("like cures like")

(ii) Principle of Minimum Dose

  9.  As a consequence of these multiple possible meanings, ambiguity in the use of the term "homeopathy" is common. The term "homeopathy" is often used to denote two or more different meanings in the same conversation or article. Conclusions drawn from research on one aspect of homeopathy (eg homeopathic medicines/products) are then applied to another meaning of the term (eg the therapeutic system of homeopathy). This confounding of meanings is most obvious in systematic reviews of "homeopathy" [1],[2],[3] and reviews of systematic reviews of "homeopathy" [4],[5]. For example, in a review entitled "A systematic review of systematic reviews of homeopathy" [4] where the primary evidence reviewed are systematic reviews of trials of homeopathic medicines, the author switches between the following terms: "homeopath" "homeopathy" "homeopathic medicines" "homeopathy's… two principles", resulting in confusion as to what conclusions might possibly refer to.

  10.  The lack of differentiation between the various possible uses of the term is further perpetuated by "homeopathy" being the only MeSH term available for searching the research evidence of homeopathy. It is of fundamental importance to distinguish between the multiple possible meanings of the term "homeopathy". We propose that the MeSH term "homeopathy" has additional subheadings to help differentiate various aspects of the therapeutic system of "homeopathy": "homeopathic medicines", "treatment by a homeopath", "the principles of homeopathy" etc and that these are used in the reporting of research eg "RCT of the efficacy of homeopathic medicine/product for …" or "An observational study of treatment by a homeopath"


  11.  Two common types of evidence called for are evidence of efficacy or effectiveness:

    (a) Evidence of efficacy is interpreted as meaning that "the treatment offers therapeutic benefits greater than placebo" [6]. Evidence of efficacy requires evidence from placebo-controlled randomised controlled trials (RCTs).

    (b) "Effectiveness" refers to the extent to which a treatment improves the outcome for patients in practice. Evidence of effectiveness requires pragmatic RCTs (which compare a treatment to treatment as usual rather than to a placebo) and well conducted observational studies of routine clinical practice which uses that treatment.

  12.  Evidence called for: The editor of the Lancet called for NICE to evaluate "homeopathy" [7] —an offer which was declined by the Department of Health. Professor Born and colleagues called for "evidence of efficacy" in their letter to the Director of NHS commissioning, ie, evidence that the treatment offers therapeutic benefits greater than placebo. However is it evidence of efficacy or is it evidence of effectiveness that is required to justify NHS spending?

  13.  Evidence required: Since 2002 NHS Primary Care Trust commissioners have been required to follow guidance from National Institute for Clinical Excellence [8] (NICE). This guidance is primarily based on clinical and cost effectiveness. Cost effectiveness is calculated by NICE using cost utility analysis which estimates the ratio between the cost of a health intervention and the benefit it produces in terms of the number of years lived in full health by the beneficiary. From an NHS commissioning perspective the primary question is one of clinical effectiveness and cost effectiveness—benefits and costs—rather than efficacy. Leading Complementary and alternative medicine researchers [9],[10],[11] concur with NICE on the importance of establishing evidence of effectiveness before seeking evidence of efficacy.

  14.  NHS spending on "homeopathy": With an estimated 120,000 visits to homeopaths in the NHS annually and an NHS expenditure of £3.3 million, [12] what is this £3.3 million being spent on? The total NHS spending on homeopathic medicines (products) does not amount to more than 5% of this total amount, the bulk of the cost of "homeopathy" in the NHS is the cost of homeopathic services—treatment by/consultations with homeopaths and the infrastructure to facilitate this. Thus the evidence required to inform the debate regarding NHS spending on "homeopathy" is largely evidence of the clinical and cost effectiveness of treatment by a homeopath, homeopathic services.

  15.  Does this evidence exist? The following paragraphs explore the evidence cited, dividing this evidence into two types: experimental and observational.

  16.  Experimental evidence is derived from situations where subjects have been randomly assigned to one of two or more groups, for instance in a randomised controlled trial (RCT). The experimental evidence base comprises published reports of trials, systematic reviews of RCTs, meta-analyses of RCTs and reviews of systematic reviews.

  17.  Since 1940, over 150 RCTs of "homeopathy" and 26 systematic reviews of "homeopathy" have been published. [13] The majority of RCTs have compared a homeopathic medicine/product to a placebo—thus providing information on the efficacy of homeopathic medicines/products. Only 14 RCTs compare homeopathic medicine to orthodox treatment and thus provide information on the comparative effectiveness of homeopathic medicines.

  18.  However the majority of NHS "homeopathy" is delivered by a homeopaths. Van Hootegem [14] in relating the case of a 23 year old woman with chronic fatigue syndrome who was cured with a course of "homeopathic" treatment states: "the action of the homeopathic medicine was intimately woven with the relationship I had with her as a therapist. It is impossible to separate these two influences"

  19.  Thompson and Thompson [15,16] have used qualitative research to identify what might be the "active ingredients" of the homeopathic approach. Through a process of direct observation and modelling in a real world context, they attempted to "identify the components of the intervention and underlying mechanisms by which they will influence outcome". Six putative active ingredients were identified which might contribute to the effectiveness of homeopathic care: patient's openness to the mind body connection, consultational empathy, in depth enquiry into bodily complaints, disclosure, the remedy matching process, homeopathic remedies. Other authors have discussed the difficulties of separating out the effects of the homeopathic medicine from the consultation effects. [17,18]

  20.  I suggest that until there is clarity as to the active ingredients in homeopathic treatment and how such ingredients relate to each other, treatment by a homeopath needs to be viewed as a complex intervention [19] (which includes homeopathic medicines/products). Thus, assessment of the effectiveness of "homeopathy", should not separate out the component parts of treatment by a homeopath—instead "homeopathy" should be assessed as a package of care as it is delivered.

  21.  Observational evidence: In addition to experimental evidence, there is a large body of observational evidence. The observational evidence base consists of observational studies (of groups of patients) and case studies (single or case series) of treatment by homeopaths. There are 22+ observational studies (12 conducted in the NHS) [20,21,22] which report the outcomes of 15,703 patients receiving treatment by a homeopath. In addition there are several hundred thousand published single case reports [23] the majority of which exist in the "grey" literature (just 507 single case reports/series are available in online databases). This body of literature provides an evidence base as to the clinical effectiveness of treatment by a homeopath (not homeopathic medicines/products per se).

  22.  The research methods used to collect observational data mean that this evidence is vulnerable to substantial biases (regression to the mean, patient selection bias, outcome measurement bias. [20] Individual case studies are often vulnerable to other forms of additional bias: observer bias, recall bias, and analysis assessment bias. Any bias may exaggerate or deflate the true effect of the treatment. Since observational evidence is prone to many types of bias, observational evidence is regarded as weaker than experimental evidence, and has been disregarded in systematic reviews of evidence (though NICE commissioned systematic reviews now include observational evidence).


  23.  The precise meaning of the term "Homeopathy" should always be stated ie

    (a) Therapeutic system of homeopathy

    (b) Homeopathic products/medicines/remedies/pillules

    (c) Homeopathic services/treatment by a homeopath

    (d) Principles of homeopathy:

(i) Principle of Similars ("like cures like")

(ii) Principle of Minimum Dose

  24.  The type of evidence called for to address a question, should match the evidence that is required to address that question, ie does this question require evidence of efficacy, clinical effectiveness, cost effectiveness, acceptability, safety..?

25.  If quality and the quantity of the existing evidence is insufficient to yield an answer, then means to provide this evidence should be sought.


1.  Shang, A, Huwiler-Muntener K, Nartey L, Juni P, Dorig S, Sterne J A et al., (2005), "Are the clinical effects of homoeopathy placebo effects? Comparative study of placebo-controlled trials of homoeopathy and allopathy". Lancet, 366, 9487, 726-32.

2.  Kleijnen, J, Knipschild, P, Riet, G R, (1991), "Trials of homoeopathy". British Medical Journal, 302, 6782, 960.

3.  Hill, C, Doyon F (1990), "Review of randomized trials of homoeopathy". Rev Epidemiol Sante Publ, 38,139-147.

4.  Ernst, E, (2002), "A systematic review of systematic reviews of homeopathy", British Journal of Clinical Pharmacy, 54,577-582.

5.  NHS Centre for Reviews and Dissemination (CRD), (2002); Effective Health Care, 7, 3, 12 . http://www.york.ac.uk/inst/crd/ehcb.htm

6.  House of Lords (2000), Session 1999-2000 6th Report. Select Committee on Science & Technology: Complementary & Alternative Medicine. London. The Stationery Office.

7.  Horton, R (2005), "The end of homoeopathy", Lancet, 366, 9487, 690.

8.  National Institute for Clinical Excellence www.nice.org.uk

9.  Fitter, M J, Thomas, K J, (1997), "Evaluating complementary therapies for use in the National Health Service: 'Horses for courses'/Part 1: The design challenge". Complementary Therapies in Medicine, 5, 90-93.

10.  Mathie, R T (2005), "Research Development in Homeopathy—a question of methods and priorities", Homeopathy 94, 73.

11.  Fonnebo, V, Grimsgaard, S, Walach, H, Ritenbaugh, C, Norheim A J, MacPherson, H, et al., (2007), "Researching complementary and alternative treatments—the gatekeepers are not at home". BMC Medical Research Methodology, 7, 7 doi10.1186/1471-2288-7-7

12.  Thomas, K J, Nicholl, J P, Coleman, P, (2001), "Use and expenditure on complementary and alternative medicine in England—a population based survey". Complementary Therapies in Medicine, 9, 1, 2-11.

13.  Dean, M E, (2004), "The trials of homeopathy", KVC Verlag, Essen.

14.  Van Hootegem, H, (2007), "Can homeopathy learn something from psychoanalysis?" Homeopathy, 96, 2, 108-112.

15.  Thompson, E A, Thompson, T D, (2006), "Placebo or non-specific effects: what are the unique ingredients in homeopathy?". Homeopath, 25, 3, 82-3.

16.  Thompson, T, (2006), "Homeopathy—what are the active ingredients? An exploratory study using the UK MRCs framework for the evaluation of complex interventions". BioMedCentral.

17.  Thomas K J, Fitter M (1997) "Evaluating complementary therapies for use in the NHS: 'Horses for courses': the design challenge". Complementary Therapies in Medicine, 1997:5:99-93.

18.  Weatherley-Jones, E, Relton, C, (2003), "Researching homeopathic treatment—Can the placebo model really be an appropriate test of homeopathy". The Homeopath, 88, 24-25.

19.  Medical Research Council (2000), "A framework for development and evaluation of RCTs for complex interventions to improve health", www.mrc.ac.uk/complex_packages.html

20.  Clover, A, (2000), "Patient benefit survey: Tunbridge Wells Homeopathic Hospital". British Homeopathic Journal, 89, 2, 68-72.

21.  Riley, D, Fischer, M, Singh, B et al. (2001), "Homeopathy and conventional medicine: an outcomes study comparing effectiveness in a primary care setting". JACM, 7, 2, 149-59.

22.  Spence, D S, Thompson, E A, Barron, E A, (2005), "Homeopathic treatment for chronic disease; a 6-year, university hospital outpatient observational study". Journal of Alternative & Complementary Medicine, 11, 5, 793-8.

23.  Personal communication with archivist of the therapeutic system of homeopathy Francis Treuherz (April 2007).

Dr Clare Relton PhD (Health Services Research), FSHom

November 2009

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