This paper was discussed by Edzard Ernst:
https://edzardernst.com/2022/01/a-new-review-of-the-efficacy-of-homeopathic-arnica-by-harald-walach-co/[*quote*]
Front Surg. 2021 Dec 17;8:680930
Is Homeopathic Arnica Effective for Postoperative Recovery? A Meta-analysis of Placebo-Controlled and Active Comparator Trials
Katharina Gaertner 1, Stephan Baumgartner 1 2 3, Harald Walach 4
1 Institute for Integrative Medicine, University of Witten/Herdecke, Herdecke, Germany.
2 Institute of Complementary and Integrative Medicine, University of Bern, Bern, Switzerland.
3 Society for Cancer Research, Arlesheim, Switzerland.
4 Change Health Science Institute, Berlin, Germany.
Abstract
Background: Homeopathic Arnica montana is used in surgery as prevention or treatment for the reduction of pain and other sequelae of surgery. Our aim was to perform a metaanalysis of clinical trials to assess efficacy of Arnica montana to reduce the inflammatory response after surgery. Method: We conducted a systematic review and metaanalysis, following a predefined protocol, of all studies on the use of homeopathic Arnica montana in surgery. We included all randomized and nonrandomized studies comparing homeopathic Arnica to a placebo or to another active comparator and calculated two quantitative metaanalyses and appropriate sensitivity analyses. We used "Hegde's g," an effect size estimator which is equivalent to a standardized mean difference corrected for small sample bias. The PROSPERO registration number is CRD42020131300. Results: 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, 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 nonrandomized studies, which converges against zero in the randomized trials. Conclusion: 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.
Free full text:
https://www.frontiersin.org/articles/10.3389/fsurg.2021.680930/fullExcerpts:
"Introduction
"Homeopathic Arnica montana has a reputation for stemming bleeding, mainly internal bleeding following internal lacerations, for instance from contusions, concussions, sprains, and other injuries (1–5). Hahnemann, the founder of Homeopathy, took this indication from European folk-medicine, where Arnica has been long in use for the treatment of sprains and lacerations. The principle of homeopathy is the law of similars, similia similibus curentur, let like be cured by like (6). Hahnemann developed an operationalization by using known toxicological data from poisonings with various plants and substances, and the symptoms that these substances produce when ingested by healthy volunteers, either crudely, or more often in potentized form (7). For this purpose, the substances are successively diluted and succussed (i.e.. vigorously shaken) in a series of dilutions, and the probability to find any molecule of the potentized substance rapidly converges to zero for homeopathic potencies beyond 24X or 12C. Hence, it is unclear how such potencies can at all be effective. However, reviews of pathogenetic trials in healthy volunteers document effects that are different from placebo, at least sometimes (8), and a recent meta-analysis shows that individualized homeopathy can be statistically separated from placebo (9). The bone of contention is of course the question as to how remedies without a known active ingredient could be at all effective. We plead ignorance here. But absence of knowledge is not knowledge of absence. It might well be possible, as has been often the case in medicine, that future theories or further research might unearth some new therapeutic principle. To understand whether this is at all a useful exercise, it is helpful to see whether the data to date would justify such efforts.
"Arnica is used a lot for self-care (10, 11) and also in midwifery (12) and surgery (13). Meanwhile, some 30 studies have been conducted where homeopathic Arnica has been applied before or after surgery to improve wound healing, stop bleeding and swelling, and reduce pain. Studies of Arnica for the prevention of muscle-soreness after sportive activities such as marathon running are negative (14, 15), and an early systematic review was skeptical about the effectiveness of Arnica (16). A recent publication summarized the effects of Arnica as found in 20 placebo-controlled trials descriptively, and the authors stated that homeopathic Arnica 'seems to have a mitigating effect on ecchymosis, most notably following rhinoplasty and facelifts/facial procedures' and claimed the importance to determine the efficacy of this possibly beneficial therapeutic intervention (17).
"Hence, we set out to conduct a systematic review and meta-analysis of clinical trials asking whether homeopathically prepared Arnica is more effective than placebo, or at least as effective as active controls in surgery for the treatment of postoperative pain, prevention of swelling, edema, and other sequelae. We deliberately focused on studies that used Arnica only and excluded trials that used a combination of remedies."
"Discussion
"In this metaanalysis of studies testing homeopathic Arnica as a medication to prevent and treat postoperative pain, bleeding, swelling, and discomfort after surgery, we found a small effect size of g = 0.18 in 18 placebo-controlled trials that missed conventional significance by a small margin, and a non-zero, not significant effect size in active comparator studies, which is likely inflated, because non-randomized studies of lower quality contribute with a large effect size.
"In comparison with a recently published systematic review on perioperative Arnica (tinctures and homeopathic potencies), our analysis adds the quantitative cumulative effects of homeopathic Arnica compared the placebo to the descriptive results and summarizes for the first time the clinical effects of homeopathic Arnica compared with an active agent (17).
"The outcomes used to document this effect in trials were varied and ranged from pain, which was documented in most of the studies, to swelling, edema, discomfort, or physical measures of range of movement. The studies were most often of smaller surgical interventions, such as carpal tunnel surgery, oral-facial, or dental surgery. The heterogeneity is high in these studies, and clearly limits the results, though it can only be partially explained according to our analysis. Studies that are of better quality have a higher effect size."
"Clinical heterogeneity due to the variety of surgical procedures may have contributed to the wide range of outcome measures."
"Thus, it would have been possible, but impractical to analyze certain outcome types separately and would likely not have changed the overall result considerably. Thus, our attempt to rather include all information and estimate a robust effect is an analytical decision that might have erred toward the conservative side. If only those studies that used placebo-controls and VAS measures of pain are considered descriptively, then the effect of Arnica can be quantified as lying between a reduction of 5 and 9 mm visual analoque scale (VAS) pain rating.
"The active comparator trials produced a small, but non-significant and heterogeneous effect size...Thus, homeopathy seems to work as well as anti-inflammatory substances, which makes sense, as these substances also have an effect over and against placebo (48, 49)."
"The effect size of the overall effect is just missing conventional significance and is small. This lack of formal significance is due to the high heterogeneity of the trials. Sensitivity analyses, see below, can clarify some of this heterogeneity. From a homeopathic point of view, a part of this might be due to the fact that Arnica is only partially indicated in surgical wounds, despite its popularity. The established homeopathic indication is blunt trauma, lacerated, internal wounds, and bleeding from such wounds (2–5). Surgical wounds with clear cuts, where tissues have not been 'violently stretched' (5) are a different indication, but due to the popularity of Arnica and because it seems such an easy indication to study, a lot of studies investigated Arnica in surgery without profound homeopathic reasoning. Our analysis shows that it is possible to use Arnica effectively in surgery, but not necessarily optimal. The variation in effect sizes is large. In some cases Arnica might be counter-indicated, especially if used in a preventive mode, as it might facilitate bleeding (11) and diminish fibrinogen (50). Only two trials were included in the sensitivity analysis of therapeutic use of Arnica with placebo-controlled trials. This might explain, why this effect is near-zero and non-significant. The majority of placebo controlled trials were preventive."
"The studies that had been conducted so far were rather small. The largest study included 237 patients, and only four studies had more than 100 participants. Considering the small overall effect size, the individual power of studies was small, which is part of the reason why this intervention is debated. However, a metaregression of study size on effect size did not reveal a significant slope, although the slope was slightly negative. Thus, study size in itself does not have any influence on effect size estimation.
"Publication bias is an unlikely explanation for our findings, as the analytical methods of publication bias used point out that either an unrealistically large number of studies would have gone unpublished or studies favoring homeopathy were unpublished, none of which is a reasonable assumption."
"The effect size is clinically small. Arnica in itself might be a suboptimal homeopathic indication for bleeding and swelling after surgery. Thus, an analysis summarizing studies with other remedies or combinations might be warranted. However, considering that Arnica is very cheap and an easy intervention, one might consider it worthwhile in cases where patients ask for it. Since the effect size is larger, when used therapeutically, and because of the underlying rationale, we would recommend using it only therapeutically, not preventively.
"We conclude that homeopathic Arnica produces a small effect size across a series of 18 placebo-controlled trials, which just misses significance, and it is equal in effectiveness to conventional non-steroidal anti-inflammatory drugs in the treatment of postoperative pain, swelling, and functional limitations."
Comments:
Unlike many homeopathy papers I have posted on, this one at least notes that homeopathy seems to be impossible according to scientific knowledge.
Here are the comments of Edzard Ernst:
"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!"
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[Formatierung verbessert, Pangwall]
