Yes, there is a new paper on homeopathic Arnica!
And yes, it arrives at a positive conclusion.
How is this possible?
Let’s have a look.
The authors conducted a systematic review and metaanalysis, following a predefined protocol, of all studies on the use of homeopathic Arnica montana in surgery. They included all randomized and nonrandomized studies comparing homeopathic Arnica to a placebo or to another active comparator and calculated two quantitative meta-analyses and appropriate sensitivity analyses.
Twenty-three publications reported on 29 different comparisons. One study had to be excluded because no data could be extracted, leaving 28 comparisons. Eighteen comparisons used placebo controls, nine comparisons an active control, and in one case Arnica was compared to no treatment. The metaanalysis of the placebo-controlled trials yielded an overall effect size of Hedge’s g = 0.18 (95% confidence interval -0.007/0.373; p = 0.059). Active comparator trials yielded a highly heterogeneous significant effect size of g = 0.26. This is mainly due to the large effect size of non-randomized studies, which converges against zero in the randomized trials.
The authors concluded that homeopathic Arnica has a small effect size over and against placebo in preventing excessive hematoma and other sequelae of surgeries. The effect is comparable to that of anti-inflammatory substances.
This review has many remarkable (or should I say, suspect?) features, e.g.:
- Its authors are famous (or should I say, infamous) advocates of homeopathy not known for their objectivity (including Prof Walach).
- Some of the trials included in the analysis are unpublished conference proceedings usually only published as an abstract (ref 29).
- Others were published in journals such as ‘Allgemeine Homoeopathische Zeitung‘ which is unlikely to manage a decent peer-review system (ref 46).
- Some trials used Arnica in low potencies that contained active molecules, and nobody doubts that active molecules can have effects (ref 32 and 37).
- One study seems to be a retrospective case-control study (ref 38).
- The primary endpoints of several studies were not those evaluated in the review (e.g. ref 42).
- One study used a combination of herbal and homeopathic arnica in the verum group which means the observed effect cannot be attributed to homeopathy (ref 31).
Perhaps the strangest feature relates to the methodology used by the review authors: “Where data were only available in graphs, data were read off the graph by enlarging the display and reading the figures with a ruler.” I have never before come across this method which must be wide open to bias.
Considering all of these odd features, I think that the small effect size over and against placebo in preventing excessive hematoma and other sequelae of surgeries reported by the review authors is most likely due to a range of factors that have nothing whatsoever to do with homeopathy.
So, does the new review show that homeopathic Arnica is “efficacious”? I don’t think so!