Here is the re-post of the review of the homoeopathy meta-analyses. This pretty much covers it for positive evidence in mainstream journals, though if you get into the homoeopaths' own fanzines there's no end to the stuff you can find. Not blinded and controlled, usually, though - their idea of proof tends to the single-patient anecdote.
Maybe we need to look at the actual clinical evidence regarding homoeopathy. After all, if the remedies don't have any effect on the likelihood of patients recovering from disease, there's not much point speculating about mechanisms of action.
There have been quite a few meta-analyses and literature reviews over the years. The first one was totally negative.
Hill, C. and F. Doyon (1990)
Review of Randomized Trials of Homoeopathy. Review D'Epidemilogie et de Sante Publique 38: 139-147.
In our opinion, the results do not provide acceptable evidence that homoeopathic treatments are effective.
The next believed that there might be something there, but couldn't really say because of the poor quality of most of the papers they'd reviewed. Remember, this is an
entire system of medicine, but they couldn't be sure whether there was any effect there at all.
Kleijnen, J., P. Knipschild and G. ter Riet (1991)
Clinical Trials of Homoeopathy. British Medical Journal 302: 316-23.
At the moment the evidence of clinical trials is positive but not sufficient to draw definitive conclusions because most trials are of low methodological quality and because of the unknown role of publication bias. This indicates that there is a legitimate case for further evaluation of homoeopathy, but only by means of well performed trials.
The homoeopathic community has three papers it regularly trots out in support of its case. This Kleijnen paper is the first, and the interesting point about that is that they usually claim that the authors state that the better the quality of the study design, the higher the chance of a positive result. In fact the paper says nothing of the sort. I suspect there is a homoeopathic resource page somewhere which makes this claim, and the proponents we encounted are merely copying information from that, with no concern whether it's right or wrong - Xanta virtually admitted as much. So, virtual Mars Bar to the first person to find this page and link to it!
The next paper to appear is never mentioned by the homoeopaths, and perhaps one can see why.
PRESCRIRE INTERNATIONAL (unattributed articles) (1996)
Homeopathy update. Prescrire International 5:21.
Despite the large number of comparative trials carried out to date there is no evidence that homeopathy is any more effective than placebo therapy given in identical conditions.
The next paper is the one the homoeopaths like to boast about most. It's certainly the most positive mainstream publication they've ever had in their favour. But even this can't say for sure that there's any effect at all!
Linde, Klaus, Nicola Clausius, Gilbert Ramirez, Dieter Melchart, Florian Eitel
et al. (1997)
Are the Clinical Effects of Homoeopathy Placebo Effects? A Meta-Analysis of Placebo-Controlled Trials. Lancet 350: 834-43.
The results of our meta-analysis are not compatible with the hypothesis that the clinical effects of homeopathy are completely due to placebo. However, we found insufficient evidence from these studies that homeopathy is clearly efficacious for any single clinical condition. Further research on homeopathy is warranted provided it is rigorous and systematic.
However, several people found the first part of that statement a bit surprising, and had a closer look at the data, with the
Bandolier article presenting a detailed analysis. The main point at issue was whether indeed there was no decline in the probability of a positive result with increasing quality of study design. Finally, goaded by the volume of critical comment, the original authors published what virtually amounted to a retraction.
Linde
et al. (1999)
Impact of Study Quality on Outcome in Placebo-Controlled Trials of Homeopathy. J. Clin. Epidemiol. 52: 7, 631-636.
We conclude that in the study set investigated, there was clear evidence that studies with better methodological quality tended to yield less positive results.
It's striking that when homoeopaths boast about the earlier Linde paper, they never get round to mentioning this one!
The third paper they present refers to a 1996 report to the European Commission on homoeopathy. This is usually represented as positive, however the 1996 document is not accessible online so I haven't been able to verify the quotes. They may be no more accurate than the representation of the Kleijnen study, for all I know. What
is available is the peer-reviewed version which was published in 2000.
Cucherat M., Haugh, M. C., Gooch, M. & Boissel, J. P. (2000)
Evidence of clinical efficacy of homeopathy. A meta-analysis of clinical trials. Eur. J. Clin. Pharmacol. 56(1): 27-33.
There is some evidence that homeopathic treatments are more effective than placebo; however, the strength of this evidence is low because of the low methodological quality of the trials. Studies of high methodological quality were more likely to be negative than the lower quality studies. Further high quality studies are needed to confirm these results.
A couple of years later another meta-analysis specifically collated the findings of these earlier papers, with paticular reference to the plethora of re-analyses of Linde's original data. Although the author of this review trained as a homoeopath, his opinion is not respected by the homoeopathic community!
ERNST, E. (2002)
A systematic review of systematic reviews of homeopathy. Br. J. Clin. Pharmacol. 54, 577-582.
Collectively [the reviews] failed to provide strong evidence in favour of homeopathy. In particular, there was no condition which responds convincingly better to homeopathic treatment than to placebo or other control interventions. Similarly, there was no homeopathic remedy that was demonstrated to yield clinical effects that are convincingly different from placebo.
A sixth meta-analysis was published more recently.
ALMEIDA, R. M. (2003)
A critical review of the possible benefits associated with homeopathic medicine. Rev. Hosp. Clin. Fac. Med. Sao Paulo,
58, 324-331.
This is very up-to-date, very penetrating, and the homoeopaths don't really seem to want to add it to their favourites list either.
As a result of the recent scientific research on homeopathy, it can be concluded that ample evidence exists to show that the homeopathic therapy is not scientifically justifiable.
It's worth repeating that these are reviews not of a single drug, or even a single class of drugs or treatment approach. Homoeopathy is represented as a
complete system of medicine, and the best it can manage in the entire canon of scientific literature is the opinion (much disputed) that it's possible there might be something there, but nobody can say for sure, and better quality research is needed. More recently, some better-quality research has been done, and I'll reference some of that in a subsequent installment. (I intend to cover, in order, well-controlled individual clinical trials from the past 10 years; evidence for the existence of "proving" effects, and controlled trials in animals. Anyone who'd like to submit a likely candidate paper in any of these categories, please feel free.)
Rolfe.
