On the plausibility of Homeopathy

Homeopathy is surrounded by a ‘credibility gap’: the claims made for it seem so improbable to many of conventional scientific background that they cannot believe the claims made for it. The debate held at the University of Connecticut last October, of which we publish a transcript in this issue, nicely exposes the issues.[ ¹ ] Six eminent speakers, both supporters of, and sceptics concerning, homeopathy debated the plausibility, theoretical principles, clinical and basic research evidence, ethical and other issues surrounding homeopathy. But there seems to have been little meeting of minds. The first speaker, Steven Novella, dealt with the scientific plausibility of homeopathy, stating that ‘There is no plausible basis for biological persistence or activity of alleged memory of water’. The following speaker, Rustum Roy, flatly contradicted him, saying ‘a number of very good research studies have shown, the structure of water can be changed easily and retain the new structure for hours and days’.

The debate about plausibility is not new: the first comprehensive systematic review of homeopathy, published over 15 years ago, said that ‘Based on this evidence, we would be ready to accept that homoeopathy can be efficacious, if mechanism of action were more plausible’.[ ² ]

A more recent review started from the premise that ‘specific effects of homoeopathic remedies seem implausible’.[ ³ ] Of course this does not excuse the remarkable opacity of this review, which gave no hint of which studies it was based on and did not include a sensitivity analysis, among other failings. Still less does it excuse a recent commentary in The Lancet[ ⁴ ] which opened with the statement that: ‘Five large meta-analyses of homoeopathy trials have been done. All have had the same result: after excluding methodologically inadequate trials and accounting for publication bias, homoeopathy produced no statistically significant benefit over placebo.’ In fact only one of the large meta-analyses of clinical trials of homeopathy included correction for both publication bias and trial quality, and it showed precisely the reverse: effects of homeopathy remained significantly greater than placebo when these, and other, corrections were applied singly or in combination.[ ⁵ ] Remarkably, the commentator omitted even to cite this article, although it was published in the same journal.

• References

• 1 Gold P.W., Novella S., Roy R., Marcus D., Bell I., Davidovitch N., Saine A. Homeopathy—quackery or a key to the future of medicine?. Homp 2008; 97: 28-33.
• 2 Kleijnen J., Knipschild P., ter Riet G. Clinical trials of homeopathy. Br Med J 1991; 302: 316-323.
• 3 3 Shang A, Huwiler-Muntener K, Nartey L, et al. Comparative study of placebo-controlled trials of homoeopathy and allopathy. Lancet 2005;366: 726–732.
• 4 Goldacre B. Comment: benefits and risks of homoeopathy. Lancet 2007; 370: 1672-1673.
• 5 5 Linde K, Clausius N, Ramirez G, et al. Are the clinical effects of homoeopathy placebo effects? A meta-analysis of placebo-controlled trials. Lancet 1997;350: 834–843.
• 6 Calabrese E.J., Baldwin L.A., Holland C. Hormesis: a highly generalizable and reproducible phenomenon with important implications for risk assessment. Risk Anal 1999; 19: 261-281.
• 7 Calabrese E.J. Paradigm lost, paradigm found: the re-emergence of hormesis as a fundamental dose response model in the toxicological sciences. Environ Pollut 2005; 138: 379-412.
• 8 Linde K. Dose-dependent reverse effects. Br Hom J 1993; 82: 186.
• 9 Bond R.A. Is paradoxical pharmacology a strategy worth pursuing?. Trends in Pharmacological Sciences 2001; 22: 273-276.
• 10 Bhatia M. Is homeopathy bleeding to death? ⟨ www.hpathy.com/ezine/editorial/2007nov.asp⟩ Accessed 26 November 2007.
• [11] Gaylard A. Straw Men and Black Swans: the philosophy of contemporary science. (Letter.). Homp 2008; 97: 49-50.
• 12 Chaplin M.F. The memory of water: an overview. Homeopathy 2007; 96: 143-150.
• 13 Teixeira J. Can water possibly have a memory? A sceptical view. Homp 2007; 96: 158-162.