Homeopathy has remained one of the most controversial medical treatments in the world. It is based on the “like cures like” principle and the idea that serial dilution of a substance renders it not less but more potent. Both of these axioms of homeopathy lack biological plausibility (Sehon and Stanley 2010). Nevertheless, homeopathy was recently cited as one of “the most popular and widely used forms of medicine in the world” (Chatfield 2011).

Advocates of homeopathy argue that homeopathy’s “clinical effectiveness cannot be disputed” (Chatfield 2011). To prove their point, they produce evidence that seems to confirm this assumption (Fisher 2011). Critics tend to counter that these data are seriously flawed—so much so that they cannot be relied upon (Bewley et al. 2011).

The aim of this article is to critically evaluate the clinical research of the research group that, in recent years, has published most of the clinical research in homeopathy.

Table 1. Click for full-size PDF.

Methods

Medline searches were conducted to identify the team that, in the period between 2005 and 2010, had published more original, clinical research in home­o­pathy than any other group world­­wide. Subsequently, all their publications were obtained and read in full. Data were extracted according to pre-defined criteria (Table 1). Each article was then critically evaluated.

Results

The most prolific research group in this area was identified to be from Berlin. Within the last five years, this team published a total of eleven clinical studies (Brinkhaus et al. 2006; Keil et al. 2008; Teut et al. 2010; Witt et al. 2005a; Witt et al. 2009a; Witt et al. 2005b; Witt et al. 2008; Witt et al. 2009c; Witt et al. 2009b; Witt et al. 2010; Witt et al. 2011) (Table 1). The articles refer to randomized clinical trials and cohort studies published in both conventional (n=7) and alternative medical journals (n=4). Most of the articles have major limitations, which will be discussed below.

Discussion

Homeopathy is not an area of buoyant research activity; the fact that one center published eleven clinical studies of homeopathy within five years is re­markable. The eleven publications fall in three categories: randomized clinical trials (RCTs); cohort studies without controls; cohort studies with controls. These will be discussed in turn.

Three RCTs of homeopathic arnica were published in one single article (Brinkhaus et al. 2006). They all in­cluded patients undergoing arthroscopic knee surgery and all used change in knee circumference after surgery as the primary outcome measure. The first study included 227 patients with arthroscopy, the second thirty-five patients with artificial knee joint implants, and the third fifty-seven patients with cruciate ligament reconstructions. No power calculations were provided. The first two RCTs showed no significant effect of peri-operative homeopathic arnica D30 compared to placebo. The third RCT did demonstrate a significant reduction of 1.8 percent. The authors also mention a post-hoc pooled analysis of all three RCTs that revealed a borderline significant effect (p=0.04). They conclude that “patients receiving arnica showed a trend toward less post-operative swell­ing compared to patients receiving placebo” (Brinkhaus et al. 2006) and recommend that the observed effects “seem to justify the use of homeopathic arnica in cruciate ligament reconstruction” (Brinkhaus et al. 2006). The authors did not critically discuss the clinically irrelevant reduction in knee circumference. The stated aims include investigating the safety of homeopathic arnica, yet the sample size is far too small for identifying rare adverse effects. No conflicts of interest were mentioned in the article (Brinkhaus et al. 2006).

This cohort study was submitted to a multitude of analyses that (so far) have been published in a total of seven articles (Teut et al. 2010; Witt et al. 2005b; Witt et al. 2008; Witt et al. 2009c; Witt et al. 2009b; Witt et al. 2010; Witt et al. 2011). The first two of them refer to the results at year two (Witt et al. 2005b), the third at year eight (Witt et al. 2008). The stated aims of the two- and eight-year follow up are, however, remarkably different (Table 1). The authors recruited 103 primary care practices in Germany and Switzerland employing homeopathy. All patients consulting the homeopathic physician for the first time were included regardless of diagnosis. About 68 percent of the patients “believed” in homeopathy. The main outcome measures were patients’ and physicians’ assessment of complaints. The questionnaire used for children had been validated, but the other outcome measures had been developed by the researchers themselves and had not been formally validated. All patients underwent an initial consultation by their homeopathic doctor lasting two hours on average.

Despite the multiple publications, only scant details were provided in the articles about the actual treatments administered. In one article, “recording all treatments” was mentioned in the meth­ods section, but the results did not provide these details (Witt et al. 2011). Half of the patients also consulted non-study physicians who were not necessarily homeopaths (Witt et al. 2005b). In the article reporting the eight-year follow-up (Witt et al. 2008), the authors state that “all physicians were completely free to choose a treatment”; presumably this included conventional therapies as well.

Despite the fact that patients had been recruited regardless of their medical condition, the conclusions of one of the articles refer to “patients with chronic diseases” (Witt et al. 2005b). The authors stress repeatedly that cause and effect cannot be inferred in a study of this nature. Yet, they repeatedly imply causal inferences, for example: “younger patients and those with more severe disease appear to benefit most from homeopathic treatment” (Witt et al. 2005b); “the effect must not be attributed to homeopathic treatment alone” (Witt et al. 2008) (implying that at least part of it can be); “fully cured: 12.2%” (Witt et al. 2011); “under homeopathic treatment the severity of the disease and the quality of life im­proved substantially, which supports the ‘whole person’ approach prevailing in contemporary homeopathy”; “homeo­pathic medical therapy may play a beneficial role in the long-term care of older adults with chronic diseases” (Teut et al. 2010).

The subsequent publications of this study relate to subgroups of patients with specific conditions at the two-year follow-up (Teut et al. 2010; Witt et al. 2009c; Witt et al. 2009b; Witt et al. 2010; Witt et al. 2011) (Table 1). The two-year follow-up results were published in two strikingly similar articles (Becker-Witt et al. 2004; Witt et al. 2005b). One of them falls outside the reporting period of the present analysis (Becker-Witt et al. 2004), and it is therefore only mentioned in the discussion of my analysis. In none of these articles was the disease in question diagnosed according to rigorous criteria. Even though sample sizes were often low (Table 1), the authors believe their results are “representative” (Witt et al. 2011).

All of these publications report highly encouraging results for homeo­pathy. The possibility that these findings might not be due to the treatment but caused by the natural history of the disease, regression toward the mean, placebo effects, the therapeutic relationship, other context effects, or a mixture of any of these factors is repeatedly mentioned but then either dismissed or deemed unlikely. In some instances, even the stated aim of the article seems to imply causality: “evaluate ... effects of homeopathic treatment” (Witt et al. 2011), “our study was designed to evaluate homeopathic treatments” (Witt et al. 2011), “evaluating homeopathic treatment” (Witt et al. 2009b), “to evaluate ... effects of an individualized homeopathic treatment” (Witt et al. 2010). Conflicts of interest were often not mentioned, but if they were, none were declared. Some of the articles in this series stated that the research was funded by the Carstens Foundation, an organization well-known for its pro-homeopathic stance.

The third category of articles (Keil et al. 2008; Witt et al. 2005a) is based on comparative cohort studies. For the first of these investigations, 493 patients with five selected chronic conditions were recruited by 101 homeopathic and fifty-nine conventional study physicians. These patients had chosen homeopathic and conventional healthcare according to their own be­liefs and preferences. Therefore, the two groups yielded numerous significant differences at baseline, e.g., conventional patients were seven years older, had used more medical services in the past, and were more likely to be male. Half of the homeopathic cohort used conventional treatments in addition to homeopathy. Only scant details were provided about the treatments ad­ministered in each group.

The main outcome measures in­cluded a non-validated symptom score, quality of life, and overall costs. The latter was only available for 38 percent of patients, which seems to invalidate any conclusions regarding cost. Yet the authors fail to discuss this point critically and present these data as valid. The results seem to indicate that homeo­pathy “had a better overall outcome compared to ... conventional treatment” (Witt et al. 2005a). The obvious fact that this could be due to a range of factors, including the lower age of these patients or the additional attention by homeo­paths, is not critically discussed.

The data of the same study were submitted to a subgroup analysis of 118 children suffering from eczema (Witt et al. 2005a). In this paper, the authors again imply causal inferences that, due to the study design, are not warranted, e.g., “the extent of the improvement was significantly different, in favour of homoeopathically treated patients” or “... it is noteworthy that the outcome was at least similar (by patients’ assessment) or significantly superior (by physicians’ assessment) to conventional treatment” (Keil et al. 2008). Again, the study is presented as though it was a comparison of homeo­pathy with conventional care, while it was, in fact, a comparison of homeopathy plus conventional care versus conventional care alone.

Witt et al. also published a separate but similar comparative cohort study with children suffering from eczema (Witt et al. 2009a). Again, the parents had selected either homeopathic or conventional based on their beliefs. Consequently, there were multiple baseline differences between the relatively small groups (n=48 and 87). Only scant details were provided about the treatments used in both groups. In particular, it is unclear to what extent the homeopathic physicians also employed conventional treatments. Neither was it clear on what basis the physicians decided to include some patients and exclude others. The primary outcome measure was a validated symptom score administered by blinded evaluators. The results showed no inter-group differences at six or twelve months, but a graph provided in the article depicts a steeper decline of the symptom score in the homeopathy group. The costs for homeopathic patients were about twice of those of the control group. Closer inspection of the results reveals that, because the homeopathic group was more severely ill at baseline, the apparent improvement in this group might have been due to a more pronounced regression toward the mean. Yet this possibility was not discussed by the authors of this paper.

This critical analysis is, of course, limited by the fact that only the publications of one research group were scrutinized. Thus, generalizations across the field of homeopathy are not permissible. Nevertheless, my evaluation suggests numerous flaws in the design, conduct, and reporting of clinical research in homeopathy recently published by the most prolific research unit in this area. It also reveals multiple publications of similar data, which might be regarded as ethically debateable. Most important, it points to a phenomenon that, according to my experience, seems to be common in this line of investigation (Ernst 2010): relatively weak data tend to be over- or misinterpreted to such an extent that the casual reader of such publications can be seriously misled. Consequently, homeopathy appears to have clinical effects which, with critical analysis, can be attributed to bias or confounding.

Future research in this area should be more rigorous and readers of biased research papers should apply appropriately critical assessments.n

References

Becker-Witt, C., R. Ludtke, T. E. Weisshuhn, et al. 2004. Diagnoses and treatment in homeopathic medical practice. Forsch Komple­mentarmed Klass Naturheilkd. 11: 98–103.

Bewley, S., E. Ernst, J. Garrow, et al. 2011. The evidence for homeopathy is not positive: A rapid response to Bewley, S., On behalf of N. Ross, A. Braillon, E. Ernst, et al. Letter: Advice on homoeopathic products: Clothing naked quackery and legitimising pseudoscience BMJ 2011; 343:doi:10.1136/bmj.d5960.

Brinkhaus, B., J.M. Wilkens, R. Lüdtke, et al. 2006. Homeopathic arnica therapy in patients receiving knee surgery: Results of three randomised double-blind trials. Com­ple­mentary Therapies in Medicine 14(4): 237–246.

Chatfield, K. 2011. Progress in the placebo debate for homeopathy? Journal of Alternative and Complementary Medicine 17(8):663–664.

Ernst, E. 2010. Classic flaws in clinical CAM research. Focus on Alternative and Comple­mentary Therapies 15(3):207–209.

Fisher, P. 2011. Homeopathy: A rapid response to Bewley, S., On behalf of N. Ross, A. Braillon, E. Ernst, et al. Letter: Advice on homoeopathic products: Clothing naked quackery and legitimising pseudoscience BMJ 2011;343:doi:10.1136/bmj.d5960.

Keil, T., C.M. Witt, S. Roll, et al. 2008. Homoeopathic versus conventional treatment of children with eczema: A comparative co­hort study. Complementary Therapies in Medicine 16(1): 15–21.

Sehon, S. and D. Stanley. 2010. Applying the simplicity principle to homeopathy: What remains? Focus on Alternative and Comple­mentary Therapies 15(1): 8–12.

Teut, M., R. Lüdtke, K. Schnabel, et al. 2010. Homeopathic treatment of elderly patients—a prospective observational study with follow-up over a two year period. BMC Geriatrics 10: 10.

Witt, C., T. Keil, D. Selim, et al. 2005a. Outcome and costs of homoeopathic and conventional treatment strategies: A comparative cohort study in patients with chronic disorders. Complementary Therapies in Medicine 13(2): 79–86.

Witt, C.M., B. Brinkhaus, D. Pach, et al. 2009a. Homoeopathic versus conventional therapy for atopic eczema in children: Medical and economic results. Dermatology 219: 329–340.

Witt, C.M., R. Lüdtke, R. Baur, et al. 2005b. Homeopathic medical practice: Long-term results of a cohort study with 3981 patients. BMC Public Health 5: 115.

Witt, C.M., R. Lüdtke, N. Mengler, et al. 2008. How healthy are chronically ill patients after eight years of homeopathic treatment? Results from a long term observational study. BMC Public Health 8: 413.

Witt, C.M., R. Lüdtke, and S.N. Willich. 2009b. Homeopathic treatment of patients with dysmenorrhea: A prospective observational study with 2 years follow-up. Archives of Gynecology and Obstetrics 280(4): 603–611.

———. 2010. Homeopathic treatment of patients with migraine: A prospective observational study with a 2-year follow-up period. Journal of Alternative and Complementary Medicine 16(4): 347–355.

———. 2011. Homeopathic treatment of patients with psoriasis—a prospective observational study with 2 years follow-up. European Journal Acta Dermatologica Venereological 23(5): 538–543.

———. 2009c. Homeopathic treatment of children with atopic eczema: A prospective observational study with two years follow-up. Acta Dermatologica Venereologica 89(2): 182–183.

Herbal medicines are currently quite popular; consumers are spending billions on them each year. Enthusiasts praise them as natural and safe, while skeptics often see them as little more than glorified placebos. The general public is frequently confused by such controversies, by a plethora of misinformation, and by the bewildering categories of medicines derived from herbs (U.S. Government Accountability Office 2010). Here I will try to clear up some of this confusion by explaining what the different categories are.

Herbal Medicines

Herbal medicines are preparations made from whole plants or whole parts of plants. They are also called botanical medicines, remedies, or supplements. Invariably they contain a mixture of ingredients, some of which may be pharmacologically active. Frequently they are marketed as dietary supplements, which are not required to have proven efficacy, safety, or quality in the United States and most other countries (Marcus and Grollman 2002, 347). Thus the spectrum is wide with both high- and low-quality products often placed side by side. Calls for tighter regulation are made regularly (e.g., U.S. Government Accountability Office 2009) but are routinely frustrated.

Herbal medicines are mostly used by consumers for self-treatment of minor symptoms. Doctors rarely employ them (except in some countries, such as Germany) and, crucially, traditional herbalists use an entirely different approach with each treatment.

The majority of herbal medicines have not been scientifically tested. But some have been adequately analyzed, standardized, and submitted to clinical trials (Ernst et al. 2006). St. John's Wort (Hypericum perforatum) is perhaps the best-investigated example. We know that this herbal antidepressant has several pharmacologically active ingredients that have been standardized in high-quality products and tested for efficacy and safety in approximately fifty clinical trials and many post-marketing surveillance studies. The results leave little doubt that St. John's Wort is efficacious for mild to moderate depression. It is also relatively safe as long as it is not combined with other drugs (Ernst et al. 2006).

When taken together with other medications, St. John's Wort can powerfully interact such that it lowers the plasma level of many drugs (Izzo and Ernst 2001, 15) which, of course, can have serious consequences. Thus the example of St. John's Wort goes some way toward demonstrating that herbal medicines can do both good and harm to patients. In other words, some herbal medicines are complicated pharmacological treatments and are biologically plausible (Schulz and Hänsel 2003).

Many other herbal medicines are not well-researched; therefore we cannot be certain about their risk-benefit profile (Ernst et al. 2006). Even the well-researched examples like St. John's Wort should be approached with healthy skepticism: the few high-quality products available are outnumbered by supplements of low quality and dubious content. Thus the market of herbal medicines is littered with products that contain little or no herbal ingredients (Sievenpiper et al. 2004, 27), are adulterated with prescription drugs (Miller and Stripp 2007, 9), or are contaminated with heavy metals (Buettner et al. 2009, 24; Cohen 2009, 361).

Synthetic Drugs Derived From Herbs

Many of our modern drugs (e.g., aspirin, Morphium, Tamoxifen, Vin­cris­tin, etc.) were originally derived from botanical material. In fact, many skeptics wonder why we cannot also extract and synthesize the active ingredients from well-researched herbal medicines such as St. John's Wort and generate single ingredients derived from that plant. This would clearly solve several problems inherent in herbal medicine, such as standardization.

While this approach of creating pure compounds does work occasionally, it fails in other instances. One reason can be the fact that herbal medicines tend to have not one but a multitude of pharmacologically active ingredients. Thus extracting only one ingredient might reduce the pharmacological activity of the whole plant extract.

Single ingredients derived from herb­al extracts can no longer be considered herbal medicines as, by definition, herbal medicines are based on the whole plant. Nevertheless, such drugs are reminders of the fact that many plants contain molecules that are pharmacologically active and can thus have both beneficial and detrimental health effects.

Traditional Herbalism

If a patient consults a Chinese, Indian, Japanese, or European herbalist, he will be diagnosed and treated according to obsolete and untested principles of diagnosis, pathophysiology, and so forth. Treatment will typically be individualized according to the characteristics of each patient and based on complex, tailor-made herbal mixtures of several (up to ten) herbal extracts. This means that ten patients suffering from depression may receive ten different, individualized concoctions, none of which might contain St. John's Wort, the only evidence-based herbal antidepressant. In other words, the biological plausibility of traditional herbalism is questionable.

Traditional herbalism is thus dramatically different from the herbal medicine described above. To scientifically test its value can be complex but it is doubtlessly possible. Few rigorous studies of this approach are currently available, and those that have been published do not support the notion that traditional herbalism is effective (Guo et al. 2007, 83).

Neither can we be certain about its safety. Because the tailor-made concoctions of traditional herbalists may contain a confusing number of active ingredients, the potential for toxicity, herb-drug interaction, contamination, and so on can be considerable. More vigorous regulation of herbalists, a subject currently being discussed in Europe (Hawkes 2010, 339), is therefore required.

Homeopathic Remedies

The public frequently confuses homeopathy with herbal medicine. The error usually arises because many homeopathic remedies are produced from "mother tinctures," which are based on herbal extracts. Thus they can carry the same (or similar) names as herbal products. The difference is that homeopathic remedies are typically highly diluted and therefore contain no active ingredients at all. Thus homeopathy lacks any biological plausibility.

Arnica is a good example. It is used as an herbal cream as well as a homeopathic remedy. Because it is toxic, Arnica should not be taken as an oral herbal medicine. Being highly diluted, homeopathic Arnica is, of course, both nontoxic and entirely ineffective (Ernst and Pittler 1998, 133).

Bach Flower Remedies

These products are currently very popular for self-medication, particularly in Europe. They are produced by placing freshly picked flowers in spring water. Thus they are also plant-derived and frequently confused with herbal medicines. After the flowers have floated for a while, the water is mixed with brandy and sold at high prices as Bach Flower Remedies.

Bach Flower Remedies were developed by the British physician Edward Bach, who had previously worked as a homeopath. His remedies have, however, little in common with homeopathy except, of course, that they are neither biologically plausible nor of proven effectiveness for any condition (Ernst 2010, 140).

Anthroposophical Medicines

Rudolf Steiner developed his anthroposophical medicines about one hundred years ago (Ernst 2008, 150). They are produced according to protocols similar to those of homeopathic remedies. Unlike homeopathy, however, anthroposophical medicine does not follow the "like cures like" principle.

As many anthroposophical medicines are based on plants, they are also often confused with herbal medicines. The best known example is Iscador®, a fermented mistletoe preparation that is a highly popular treatment for cancer in Europe. Numerous trials exist, but collectively their results do not show that this is an effective therapy (Horneber et al. 2008, 16).

Conclusion

Many articles on herbal medicine conclude by stating that more research is needed. Between 1999 and 2007, the National Institutes of Health has spent US $1.9 billion on research into dietary supplements (Regan, Wambogo, and Haggans 2011, 141). Not all of this money was well invested (Ernst et al. 2011). I therefore advocate not necessarily more research but better-designed studies into the few plausibly beneficial aspects of herbal medicine. n

References

Buettner, C., K.J. Mukamal, P. Gardiner, et al. 2009. Herbal supplement use and blood lead levels of United States adults. Journal of General Internal Medicine 24(11): 1175-82.

Cohen, P.A. 2009. American roulette: Con­taminated dietary supplements. New Eng­land Journal of Medicine 361(16): 1523-25.

Ernst, E. 2008. Anthroposophic medicine: A critical analysis [in German]. MMW Fortschritte der Medizin 150(Suppl. 1):1-6.

---. 2010. Bach flower remedies: A systematic review of randomised clinical trials. Swiss Medical Weekly 140: w13079.

Ernst, E., and M.H. Pittler, 1998. Efficacy of homeopathic arnica: A systematic review of placebo-controlled clinical trials. Archives of Surgery 133(11): 1187-90.

Ernst, E., M.H. Pittler, B. Wider, et al. 2006. The Desktop Guide to Complementary and Alternative Medicine, 2nd ed. Edinburgh: Elsevier Mosby.

Ernst, E., S.K. Hung, and Y. Clement. 2011. NCCAM-funded RCTs of herbal medicines: An important critical assessment. Perfusion 24(3) 89-102.

Guo, R., P.H. Canter, and E. Ernst. 2007. A systematic review of randomised clinical trials of individualised herbal medicine in any indication. Postgraduate Medical Journal 83(984): 633-37.

Hawkes, N. 2010. A spanner in the herbal works. BMJ 339: b5441.

Horneber, M.A., G. Bueschel, R. Huber, et al. 2008. Mistletoe therapy in oncology. Cochrane Database Systems Review 16(2): CD003297.

Izzo, A.A., and E. Ernst. 2001. Interactions between herbal medicines and prescribed drugs: A systematic review. Drugs 15: 2163-75.

Marcus, D.M., and A.P. Grollman. 2002. Botanical medicines: The need for new regulations. New England Journal of Medicine 347(25): 2073-76.

Miller, G.M., and R. Stripp. 2007. A study of western pharmaceuticals contained within samples of Chinese herbal/patent medicines collected from New York City's Chinatown. Legal Medicine 9(5): 258-64.

Regan, K.S., E.A. Wambogo, and C.J. Haggans. 2011. NIH and USDA funding of dietary supplement research, 1999-2007. Journal of Nutrition 141(1):1-3.

Schulz, V., and R. Hänsel. 2003. Rational phytotherapie: A physician's guide to herbal medicine, 5th ed. Berlin: Springer-Verlag.

Sievenpiper, J.L., J.T. Arnason, E. Vidgen, et al. 2004. A systematic quantitative analysis of the literature of the high variability in ginseng (Panax spp.): Should ginseng be trusted in diabetes? Diabetes Care 27(3): 839-40.

U.S. Government Accountability Office. 2009. Dietary Supplements: FDA Should Take Further Actions to Improve Oversight and Consumer Understanding. United States Accountability Office, January: Report to Con­gressional Requesters. GAO-09-250. Available online at www.gao.gov/new.items/d09250.pdf.

---. 2010. Herbal Dietary Supplements: Examples of Deceptive or Questionable Marketing Practices and Potentially Danger­ous Advice. United States Govern­ment Accountability Office, May 26: Testimony Before the Special Commitee on Aging, U.S. Senate. GAO-10-662T. Available online at www.gao.gov/new.items/d10662t.pdf.

When we think of conflicts of interest, we almost automatically think of money. In my area of research, complementary alternative medicine (CAM), there is no money—well, almost none (contrasted with most areas of mainstream medicine). Despite this fact, conflicts of interest are rife in CAM research. I am, of course, talking about a different type of conflict: the one that is created by strong belief and evangelic conviction.

Across the globe, I personally know many individuals who are full-time CAM researchers. They have different personalities, backgrounds, and skills. But they all have, as far as I can see, one characteristic in common: they are strong believers in the benefit of at least some aspects of CAM. On the one hand, this may seem entirely reasonable: if one didn’t believe in CAM, why would one dedicate one’s career to investigating it?

On the other hand, if the vast majority of CAM researchers are made up of CAM believers, things might not be quite right either. In other areas of medical research, the situation is—in my experience—very different. I know many pharmacologists, for instance, who are keenly aware of the dangers of medicines and extremely critical of some of the activities of the pharmaceutical industry. I cannot say that I know many CAM researchers who are truly concerned about the dangers of CAM or of the activities of those individuals or organisations that promote CAM uncritically.

Conflicts of interest are precarious because they tend to cloud judgment and generate bias—the type of bias that creeps in unnoticed and cannot be readily identified when studying a published paper. After some detective work, we might be able to find out, for example, that a certain paper that draws positive conclusions about the homeopathic remedy Traumeel® (Schneider et al. 2008) was coauthored by at least one “expert” who is on the payroll of the manufacturer of that very remedy—even if the paper itself fails to disclose this fact (Schneider et al. 2008). But what about more subtle yet potentially powerful conflicts of interest? I fear that they have far too much impact on CAM.

If the totality of researchers in one field is open to unidirectional bias, one has to worry about the area as a whole. The danger, then, is obvious: the field will collectively lose its balance and make serious and repetitive mistakes without even noticing them. In the absence of criticism “from the inside,” such an area of research can neither prosper nor mature. In my experience, CAM has very little internal criticism, as the following examples suggest.

Chiropractic

After the British Chiropractic Association (BCA) sued science writer Simon Singh for libel, the United Kingdom’s General Chiropractic Council (GCC, the regulatory body of its members) was inundated with about 700 complaints from skeptical bloggers about chiropractors who had made similarly bogus therapeutic claims. The GCC reacted by commissioning North American chiropractors to write an “evidence report.” Presumably, the GCC hoped that the report could clarify the evidence regarding the disputed claims. Bronfort et al.’s (2010) published report revealed no strong evidence for “manual therapies.” Despite this seemingly critical stance, the report is still not critical enough, in my opinion. The reason becomes clear upon a reading of its fine print. Even though the authors repeatedly mention the “quality of the evidence,” they fail to formally evaluate it. Thus, poor-quality primary studies are taken at face value, which inevitably leads to false-positive conclusions. Without the very obvious conflict of interest (chiropractors commissioned by the GCC), the report might have been far more critical than it turned out to be.

A similar situation occurs with systematic reviews of chiropractic as a treatment for specific conditions. Such articles are now emerging regularly, and they tend to display interesting discrepancies. For example, a review on the subject of asthma written by four chiropractors concluded that “chiropractic care showed improvement in subjective measures . . .” (Kaminskyj et al. 2010). Meanwhile, my own review, which included a critical assessment of the quality of the primary data, stated that “spinal manipulation is not an effective treatment for asthma” (Ernst 2009). Here I should mention perhaps that I, as an independent academic, have no conflicts of interest and receive no payments from Big Pharma or similar institutions that might have an axe to grind.

Years ago, I had already noted that reviews published by chiropractors tend to arrive at positive conclusions while those by independent experts do not (Ernst and Canter 2006). The explanation for this phenomenon seems to be simple: conflict of interest.

Acupuncture

Vickers et al. (1998) and others (Tang, Zhan, and Ernst 1999) have shown that 100 percent of all acupuncture trials originating in China report positive results. Recently, an in-depth analysis of acupuncture articles published between 1991 and 2009 revealed that China is now producing more acupuncture research papers than any other country (Han and Ho 2011). To make matters worse, this analysis also names the journals that publish the bulk of these articles: unsurprisingly, they tend to be the ones I have previously identified as publishing virtually no negative results (Ernst and Pittler 1997). Thus there is reason to fear that we are currently exposed to a mountain of research on acupuncture, much of which might be less than reliable.

Here the explanations might be more complex, and there could be more than one factor at play. Yet I have little doubt which one is the most important: conflict of interest.

What Can Be Done?

My message is clear: non-financial conflicts of interest can be just as powerful as financial ones, and in my area of research they seem to be quite overpowering. This problem will inevitably lead to significant distortions of the truth about the value of alternative medicine. The issue at hand is more than just academic: misleading results in health care endanger our health.

It is relatively easy to identify the problem, yet it is hard to solve it. I don’t pretend to have the ideal solution. All I can suggest is that journal editors consider making their authors’ conflicts of interest transparent and that readers of such papers apply a healthy dose of skepticism. Whenever there are two discrepant opinions (and that is the case more often than not), my advice is to determine which one might be prompted by a conflict of interest. In theory, this sounds fine; in practice, I am afraid, it will not be nearly enough to remedy the problem.

References

Bronfort, G., M. Haas, R. Evans, B. Leninger, and J. Triano. 2010. Effectiveness of manual therapies: The UK evidence report. Chiropractic and Osteopathy 18(3). doi: 10.1186/1746-13 40-18-3.

Ernst, E. 2009. Spinal manipulation for asthma: A systematic review of randomised clinical trials. Respiratory Medicine 103(12): 1791–95.

Ernst, E., and P. Canter. 2006. A systematic review of systematic reviews of spinal manipulation. Journal of the Royal Society of Medicine 99(4): 192–96.

Ernst, E., and M.H. Pittler. 1997. Alternative therapy bias. Nature 385: 480.

Han, J.S., and Y.S. Ho. 2011. Global trends and performances of acupuncture research. Neuroscience and Behavioural Reviews 35(3): 680–87.

Kaminskyj, A., M. Frazier, K. Johnstone, and B.J. Gleberzon. 2010. Chiropractic care for patients with asthma: A systematic review of the literature. Journal of Canadian Chiropractic Association 54(1): 24–32.

Schneider, C., B. Schneider, J. Hanisch, and R. Van Haselen. 2008. The role of homoeopathic preparation compared with conventional therapy in the treatment of injuries: An observational cohort study. Complementary Therapies in Medicine 16(1): 22–27.

Tang, J.L., S.Y. Zhan, and E. Ernst. 1999. Review of randomised controlled trials of traditional Chinese medicine. BMJ 319 (7203): 160–61.

Vickers, A., N. Goyal, R. Harland, and R. Rees. 1998. Do certain countries produce only positive results? A systematic review of controlled trials. Controlled Clinical Trials 19(2): 159–66.

It is not difficult to set up experiments that seemingly “prove” that bogus treatments work. Health journalists, in particular, are regularly taken in by such bogus studies, and the misleading results are subsequently reported in the press, perpetuating the public’s belief in these treatments.

I will give several examples from the realm of “alternative” medicine. They are, of course, entirely fictitious. Not that there is a shortage of real ones, but these days one has to be careful not to end up in the hands of libel lawyers (see “Keep Libel Out of Science,” SI, May/June 2010).

Bogus Experiment No. 1

Most clinical trials test whether one treatment is better than another. These studies are called “superiority trials.” Other studies are aimed at testing whether one therapy is as effective as another. They are called “equivalence trials.” My first example is an equivalence trial comparing a highly dilute homeopathic remedy with an accepted and well-known drug, say paracetamol (known in the U.S. as acetaminophen). Take two hundred patients with a sprained ankle and randomize them to take homeopathic arnica (the experimental treatment) or paracetamol (the control treatment). One or two days later, measure the swelling of the injured ankle as an undeniably objective outcome measure. The results will show that the swelling diminished in both groups and that no difference between the two groups emerged. The conclusion, therefore, is that both are equally effective; however, homeopathy (not having any actual active ingredient) caused fewer adverse events. The headline in the papers might read: “Homeopathy Better than Paracetamol.”

The trick here is to select an outcome measure that is not affected by the “accepted and well-known” drug. Paracetamol does not reduce swelling, and few people would claim otherwise. Thus, it acts as a placebo. Comparing two different placebos should always result in equivalence. Yet the illusion can be quite convincing.

Bogus Experiment No. 2

My second fictitious study is also an equivalence trial. It compares homeopathic care against conventional medicine for a serious chronic condition, say Crohn’s disease. Twenty patients are randomized to be treated with either approach. The results demonstrate that the carefully chosen endpoint (e.g., a symptom score) reveals no differences between the groups. The conclusion: homeopathy is as effective as standard treatment of Crohn’s disease. The headline this time? “Homeopathy Scientifically Proven to Work for Life-Threatening Diseases.”

The trick here is to underpower the study dramatically. Underpowered equivalence trials will tend to (falsely) suggest equivalence between the two tested approaches—a safe bet for illusionists.

Bogus Experiment No. 3

Another approach is to conduct a “pragmatic” trial. Such studies are currently very popular because, according to their proponents, they best reflect the “real life” situation of clinical practice. In this trial, chronically ill patients are randomized to receive either standard care (the control group) or standard care plus homeopathy (the experimental group). The primary measure of outcome for that study could be patient satisfaction, well-being, quality of life, or some other subjective endpoint. Due to the regular, lengthy, empathetic encounters received by the latter group, patients are bound to feel better and improve. Illusionists will then interpret this benefit as being caused by the specific effects of the homeopathic remedies. The headline: “Homeopathy Proven to Help Chronically Ill Patients.”

The trick, in this case, is that A (standard care) plus B (homeopathy) is always more than A alone (A<A+B)—unless, of course, B is zero. But an empathetic encounter does, of course, have an impact on many subjective outcome measures. If, in clinical trials, we do not control for nonspecific effects, it is always easy to make a treatment look effective, even in a randomized trial.

Bogus Experiment No. 4

My last illusionists’ stunt is an animal study. Such experiments, it is often (falsely) claimed, are not affected by placebo effects. Ten experimental rats receive a diet to which either a homeopathic product or a placebo is added. The aim here is not to test for therapeutic effects but to find out whether homeopathy can cause a biological effect in principle. All conceivable types of bias and confounding are excluded. The study can be designed to be completely watertight. The rats receive the treatments and are observed for several weeks. At the end of this period, all rats in the homeopathy group have died, but all of the control animals are alive. The conclusion: homeopathy generates biological effects and is thus different from placebo. The headline: “Animal Experiments Prove the Principles of Homeopathy.”

The trick is simple: we need only to select the right “remedy” (and “hide” this in the small print of the experiment). For my fictitious experiment, I chose a “mothertincture” of arsenic. This is pure, undiluted, and very toxic arsenic, yet it is strictly speaking a homeopathic preparation.

The conclusion? Bogus experiments are not difficult to set up, and it is not difficult to fool uncritical people with their results. But they are still only tricks of illusionists who aim to mislead us. It follows that, if we fail to apply our skills of critical assessment or, worse still, we never had such skills, illusionists pretending to be scientists can be a menace.

Today the climate has changed fundamentally. Complementary therapies seem to be encouraged everywhere. A government-sponsored patient guide published by the Prince of Wales’s Foundation for Integrated Health reads like a promotional brochure for complementary practitioners. The recent “Smallwood Report,” which was commissioned directly by Prince Charles (and funded by Dame Porter), goes one decisive step further: it advocates homeopathy as “an alternative” to conventional asthma treatments. And in his WHO address, Prince Charles again spoke out in favor of complementary medicine: “We need to re-discover and re-integrate some of the knowledge and well-tried practices that have been accumulated over thousand of years.”

With all this plugging and promoting, few people seem to bother about the scientific evidence. Is there, for instance, reasonable proof that homeopathy treats asthma effectively? If not, such advice could actually kill hundreds of British asthma patients per year! The answer is that the totality of the best evidence available today fails to show that homeopathy works for asthma. We therefore have a case in which the current trend toward “integrated health” is disclosed as being detrimental to the health of the nation.

Nonetheless, “integrated healthcare” is being pushed at all cost as the new buzzword for providing complementary medicine to the masses. According to Prince Charles, “We need to harness the best of modern science and technology, but not at the expense of losing the best of what complementary approaches have to offer. That is integrated health—it really is that simple.” In his WHO address he put it differently: “I believe that the proper mix of proven complementary, traditional, and modern remedies, which emphasizes the active participation of the patient, can help to create a powerful healing force for our world.”

This statement, it seems to me, is in fairly good agreement with the view expressed in a recent letter by thirteen British doctors (I was one of them) to all National Health Service (NHS) trusts. We urged the NHS to use those treatments (complementary or orthodox) that are backed up by good evidence and abandon those that are not. In other words, we did something entirely obvious and legitimate: we advocated the application of the rules of evidence-based medicine and pleaded for a single standard in healthcare. One could argue that Prince Charles’s public statements are a lay person’s expression of the concepts of evidence-based medicine. Great! I am delighted. But let’s be honest. If he means what he says, he should forthwith instruct all who work for him to stop promoting unproven or disproven treatments.

My team and I have researched complementary treatments for thirteen years. We have found many that generate more good than harm and many that don’t. In the second edition of our Desktop Guide to Complementary and Alternative Medicine (just published by Elsevier), we summarize the evidence in fifty-two different situations where one complementary therapy or another is unquestionably effective and many others where effectiveness is likely. If we all, including Prince Charles and his Foundation for Integrated Health, use this type of evidence wisely we can maximize the benefits of complementary medicine with minimal risk. But this approach requires critical analysis rather than unquestioning belief—and we don’t even need a new name for it. It’s called evidence-based medicine.