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Professor, University of Exeter, Department of Complementary Medicine, Postgraduate Medical School.
Correspondence to: Edzard Ernst, MD, PhD, 25 Victoria Park Road, Exeter EX2 4NT, UK
Complementary/alternative medicine (CAM) has become an increasingly topical theme in respiratory medicine. It has been defined as "diagnosis, treatment and/or prevention which complements mainstream medicine by contributing to a common whole, by satisfying a demand not met by orthodoxy or by diversifying the conceptual frameworks of medicine."1 CAM comprises well over 100 different therapies, which have little in common. Each therapy proclaims to be a veritable panacea.2 Some of the most prevalent complementary treatments are acupuncture, aromatherapy, herbalism (phytotherapy), homoeopathy, reflexology, and spinal manipulation (chiropractic and osteopathy). For asthma, the most frequently tried therapies are breathing techniques (including yoga), herbalism, acupuncture, and homoeopathy,3 but the whole spectrum of CAM is also used.
CAM has become an important topic because it has grown immensely popular and increasingly profitable. In the United States, 40% of the general population is using some form of CAM.5 With asthma patients, the prevalence figures may be even higher. A recent survey by the United Kingdom National Asthma Campaign3 showed that only 41% of all 4,741 respondents had never tried any type of CAM, and 33% of all asthmatic children have experience with CAM.4 It is therefore timely to ask whether CAM is, at all, evidence based.
CAM is often perceived as effective by those who use it. For instance, in the above survey,3 43% of asthma patients thought that breathing techniques were useful to "a great" or "some" extent. For acupuncture, this figure amounted to 44%, herbalism, 42%, and homoeopathy, 43%.3 Perceived effectiveness, however, is composed of specific and nonspecific effectiveness, ie, therapeutic success can be brought about by a specific mechanism of the given treatment (eg, endorphin release after acupuncture, pharmacologic actions of herbal constituents), or by factors not directly related to the therapy (eg, empathy, time spent with the patient, expectation, etc). Each of the two elements can vary in size from 0% to approximately 100% of the total therapeutic effect.6 It seems obvious that rigorous research should differentiate the nonspecific from the specific effects, because in the final analysis, this is in the interest of the asthma patient.
There are still too few investigations into the effectiveness of CAM for asthma. A systematic search7 of the available data revealed that randomized controlled trials existed only for acupuncture (n = 13), herbalism (n = 2), homoeopathy (n = 2), hypnosis (n = 2), spinal manipulation (n = 1), reflexology (n = 1), relaxation/meditation (n = 9), and yoga (n = 3). Studies of CAM also tend to be methodologically flawed,8 and the emerging evidence is usually contradictory. Therefore, systematic reviews could provide the best possible summary of the existing knowledge.9 (The selective citation of evidence fitting a particular hypothesis seems to be disappointingly prevalent in CAM,10 but it can be seriously misleading.) The conclusions of all systematic reviews of CAM include the following: (1) Breathing techniques: "Too few studies have been carried out to warrant firm judgments"11 ; and (2) Acupuncture: "It is not yet possible to make any recommendations to patients, their physicians or acupuncturists about the practice of acupuncture in the treatment of asthma on the basis of the data currently reported."12
As for homoeopathy and asthma, there were no positive results found by a thorough meta-analysis of all randomized or placebo-controlled trials.13 For the other above-named treatments, no systematic reviews in relation to asthma are available.
This disappointing state of affairs is difficult to reconcile with the success of CAM in everyday clinical practice. About 80% of all individuals (not just asthma sufferers) using CAM are satisfied with it.14 To a large extent, this could be due to the quality and character of care more than the specifics of the given therapy. For instance, a recent survey, showed that patients who use CAM and mainstream medicine in parallel (not for asthma), consistently rate the quality of the therapeutic relationship with CAM practitioners higher than that with conventional doctors.15 We should, however, remember that absence of evidence must never be confused with evidence of absence for efficacy (or safety).
Even if a given (complementary or orthodox) treatment were entirely devoid of specific effects, this would not necessarily mean that it is totally useless. There may be a case for "evidence-based placebo treatments" as an adjunct to conventional asthma treatment.16 Nonspecific effects can undoubtedly be an important part of the total therapeutic effect of any treatment, mainstream or complementary.6 This area is much neglected by present research. We need to understand the determinants of nonspecific effects better than we do at present.17 This type of inquiry is not aimed at denigrating CAM. Its objective is to determine how to optimize nonspecific effects and to find out how they can be used more widely to benefit the patient. Also, there may be important lessons to learn for mainstream respiratory medicine.
One essential precondition would, however, be the safety of the interventions in question. CAM is often promoted and perceived to be entirely riskfree. Yet, practitioners should know better, and patients should not be misled. Quite simply, there will never be a therapy that is totally devoid of risk. In conventional medicine, risks are routinely recognized, monitored, and quantified. This is necessary for balancing them against the potential benefit of a given treatment. We will employ a therapy only if the benefits outweigh the potential risks. What probably sounds like a platitude to respiratory physicians amounts to a veritable revolution for CAM where comparable risk benefit analyses are rarely possible. Not only are we uncertain about the benefits of most complementary therapies (see above), we also know far too little about the risks of CAM. All we do know is that complications, even serious ones, are on record,18 but we cannot even begin to estimate their frequency. Some of these risks include the following: (1) Acupuncture can cause trauma of vital tissue (eg, pneumothorax or cardiac tamponade); (2) Acupuncture can cause systemic infections (eg, hepatitis); (3) Some herbal remedies are hepatotoxic; (4) Some unregulated herbal remedies are adulterated (eg, with heavy metals or conventional drugs); and (5) Homoeopaths believe that their remedies cause (often severe) aggravation of symptoms in about 25% of all cases.
In addition to direct adverse effects, there is a further, even more neglected safety issue; even if a given form of CAM were entirely safe, the complementary practitioner who administers it may not be. Examples of this could be the overuse of radiographs by chiropractors19 or the advice against immunizations offered by some nonphysician homoeopaths and chiropractors.20
All experts agree that rigorous research must be conducted. As a first step, systematic reviews should establish what is already known and define specific research questions. Subsequently, these should be addressed with the most rigorous research design possible. It is true that in CAM some trials cannot be double-blind and placebo-controlled. Yet, there is no excuse for introducing double standards: randomized clinical trials are usually possible and always desirable.21 `Evidence-based CAM' must no longer remain a contradiction in terms. We need to advise our patients responsibly about the risks and benefits of these treatments.22 Neglecting this challenge would be neglecting the best interests of our patients.
References
geforen 117,2469-2473[Medline]
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