|
Sir,
We wish to raise a number of concerns about the meta-analysis of
homoeopathy by Shang et al(1). It is based on 110 trials of
homeopathy and 110 trials of conventional medicine, which are said
to be matched to the homeopathy trials, although the criteria for
matching are not clearly stated. The studies were not well matched
in respect of at least one crucial parameter: trial quality. This
was higher for the homeopathy studies (table 2).
Although the funnel plots are similar (figure 2), the conclusion
that ‘the clinical effects of homeopathy are placebo effects’ is
based on only eight, anonymous, clinical trials. These studies are
not referenced and no information about them is given, but 93% were
excluded. The quality criteria are standard measures of internal
validity, but before the conclusion, a further criterion, study
size, is added. We wonder how sensitive this analysis is to changes
in these cut-off points, for instance what is the result for the 21
homeopathy trials of ‘higher quality’? The opacity of this paper
means that it fails a key test of a good scientific report: that a
reader should, in principle, be able to reproduce it on the basis
of the report.
This paper also highlights the dangers of relying exclusively on
measures of internal validity. A number of studies of homeopathy
have been criticised for their use of inappropriate outcome
measures: for instance a study of homeopathic treatment of
childhood asthma, which would have scored as high quality on these
criteria, was reported negative (2), but as the subsequent
correspondence showed, was fundamentally flawed by a ‘ceiling
effect’.(3),(4),(5),(6) In terms of external validity, the
trial was meaningless. A study which may have been included in the
final eight looked at the use of a homeopathic medicine for
prophylaxis of influenza, an indication for which it is not
recommended, and obscured the identity of the homeopathic
medication(7). However a Cochrane Review has concluded that
it is probably effective for treatment of flu-like conditions
.(8) A number of other instances could be cited, but since
we don’t know which studies are under discussion, there is little
point.
There are also concerns about the comprehensiveness of the
literature review, some apparently eligible studies were not
included (9),(10),(11),(12),(13), others appear to have been
inappropriately included(14),(15)
Shang et al state that ‘eight trials of homoeopathic remedies in
acute infections of the upper respiratory tract …indicated a
substantial beneficial effect…sensitivity analyses might suggest
that there is robust evidence that the treatment under
investigation works. However, the biases that are prevalent in
these publications, as shown by our study, might promote the
conclusion that the results cannot be trusted.’ They state that 8
studies is too few to question their conclusion about the whole set
of publications. Their conclusion about the whole set, however, was
also based on 8 studies. The authors simply refuse to believe the
results of clinical trials of homeopathy which yield positive
results.
Shang et al also fail to quote emerging evidence for in vitro
activity of ultramolecular dilutions (16),(17) data which
has important implications for the implausibility of the claims
made for homeopathy.
The accompanying editorial portentously proclaims the end of
homeopathy(18), although the report on the leaked WHO draft
document on homoeopathy(19) is more realistic when it says
that homeopathy is popular and its use increasing (in the US sales
of homeopathic medicines grew 500% in a 7 -year period i n the
1990’s(20)). We agree with the editorial that the time has
passed for selective analyses and biased reports, but find it
ironic that this editorial rides on the back of just such a
report.
Yours sincerely
1 Shang A, Huwiler-Müntener K, Nartey L et al. Are the
clinical effects of homoeopathy placebo effects? Comparative study
of placebo-controlled trials of homoeopathy and allopathy. Lancet
2005;366:726-732
2 White A, Slade P, Hunt C, Hart A, Ernst E. Individualised
homeopathy as an adjunct in the treatment of childhood asthma: a
randomised placebo controlled trial. Thorax 2003:58: 317-21.
3 Dantas F. Homeopathy in childhood asthma. Thorax
2003;58:826. (Lett)
4 Brien SB, Lewith G. Homeopathy in childhood asthma. Thorax
2003;58:826-7. (Lett)
5 Fisher P, Chatfield K, Mathie R. Homeopathy in childhood
asthma. Thorax 2003;58:827. (Lett)
6 Leckridge R. Homeopathy in childhood asthma. Thorax
2003;58:827-8. (Lett)
7 Attena F, Toscano G, Agozzino E, del Giudice N. A
randomized trial in the prevention of influenza-like syndromes by
homeopathic management. Rev Epidémiol Santé Publ 1995; 43:
380–82.
8 Vickers A, Smith C. Homoeopathic Oscillococcinum for
preventing and treating influenza and influenza-like syndromes.
(Cochrane review). Cochrane Library 2005:3
9 Fisher P. Scott DL. A randomized controlled trial of
homeopathy in rheumatoid arthritis. Rheumatology 2001.
4:1052-5.
10 Benzecri J.P., Maïti G.D., Belon P., Questel R.
Comparaison entre quatre méthodes de sevrage après une
thérapeutique anxiolytique. Les Cahiers de l'Analyse de Données,
1991 ;16: 389-402
11 Zicari D., Ricciotti F., Vingolo E.M., Zicari N.
Valutazione dell'azione angioprotettiva dell' arnica nel
trattamento della retinopatia diabetica. Boll. Ocul, 1992 ; 71:
841-848.
12 Lewith G T, Watkins A D, Hyland M E et al. Use of
ultramolecular potencies of allergen to treat asthmatic people
allergic to house dust mite: double blind randomised controlled
clinical trial. Use of ultramolecular potencies of allergen to
treat asthmatic people allergic to house dust mite: double blind
randomised controlled clinical trial. BMJ 2002;324:520-3.
14 Davies AE. Clinical investigations into the action of
potencies. Br Homoeopath J 1971; 60: 36–41.
15 Stevinson C, Devaraj VS, Fountain-Barber A, Hawkins S,
Ernst E. Homeopathic arnica for prevention of pain and bruising:
randomized placebo-controlled trial in hand surgery. J R Soc Med
2003; 96: 60–65.
16 Belon P, Cumps J, Ennis M, et al. Histamine dilutions
modulate basophil activation. Inflamm.Res 2004; 53:181-188.
17 Rey L. Thermoluminesence of ultra-high dilutions of
lithium chloride and sodium chloride. Physica A 2003; 323:67-74
18 The end of homoeopathy. Lancet 2005;366:690.
19 Critics slam draft WHO report on homoeopathy.
Lancet;366:705-6.
20 Eisenberg DM, Davis RB, Ettner SL, Appel S et al. Trends
in alternative medicine use in the United States, 1990-1997:
Results of a follow-up national survey. JAMA. 1998;
280:1569-1576
Back
|
