Medicine and books: The Powerful Placebo: From Ancient Priest to Modern Physician
Authors: Vernon Oh
Journal: BMJ (1998)

Arthur K Shapiro, Elaine Shapiro 

The Johns Hopkins University Press, £33, pp 280 

ISBN 08018 5569 1 

Complementary Medicine: A Research Perspective

Charles Vincent, Adrian Furnham 

John Wiley & Sons, £24.95, pp 305 

ISBN 0 471 99645 2 

Both patients and doctor want to know the effectiveness and risks of complementary treatments. One issue concerning effectiveness is the extent to which placebo operates in different complementary treatments. Although all patients are not interested in mechanisms of action, the inconsistency of the placebo effect even in the same patient will influence the place of complementary treatments in the management of disease. 

In The Powerful Placebo, the Shapiros confine the terms “placebo” and “placebo effect” to treatments and treatment effects respectively, to avoid confusion with the phenomenon of “suggestion” in laboratory experiments and hypnosis. “Placebo” formerly encompassed both drug and non-drug treatments of disease, but with the proliferation of controlled treatment trials since the 1950s the term has come to mean an “inert” substance or procedure used as a control in bioscience experiments, in particular clinical drug trials. The psychiatrist authors plead for a re-widening of the concept to cover all treatments, including psychotherapy. They define placebo as “any treatment, or component thereof, which is knowingly used for its non-specific physiological or psychophysiological therapeutic effect, but is without specific activity.” 

Readers may still have difficulty in grasping a phenomenon associated with diverse orthodox treatments, both physicochemically active and inactive, in diverse organic and psychological disorders. Indeed, it is clear that all treatments have a psychological effect when given to a conscious person. In this sense, all treatments can produce placebo effects. We should therefore expect the placebo effect to be linked to complementary treatments. However, we should also realise that finding a placebo effect does not imply that the associated treatment, whether orthodox or complementary, is a placebo. Indeed, a highly effective treatment magnifies the placebo effect. Furthermore, the discovery of a powerful placebo effect does not mean that it is entirely psychologically mediated. 

How do these conclusions help us understand the contribution of placebo to complementary treatments? The author’s insights are mainly helpful in relation to the design of matching placebo controls, or active controls, and the preservation of blinding in randomised, double blind studies. The authors do not explore in depth the complex relation between placebo and complementary medicine. 

Complementary Medicine is aimed at alternative practitioners, lay people, some of whom are potential “participants” in placebo controlled trials of complementary treatments, and orthodox physicians. The authors review studies of the main modalities of complementary medicine, focusing on the effectiveness of individual treatments. Phil Richardson’s chapter evaluating the placebo effect is especially incisive. The authors maintain a balanced perspective throughout and argue for a fusion of attitudes between orthodox and complementary practitioners for the purpose of jointly carrying out randomised controlled studies of the effectiveness of complementary therapies, if possible to Popperian standards of scientific rigour. 

The problem with observational evidence for the effectiveness of complementary methods lies with four key factors. Firstly, some people who seek complementary care have lost confidence in orthodox medicine, expect a positive outcome from complementary treatments, and so experience a strong placebo benefit. Secondly, the overreporting of symptoms before, and underreporting after, any treatment introduces systematic bias. Thirdly, most complementary practitioners tailor their multifaceted treatments to individuals, thereby undermining the standardisation of treatment. Lastly, measuring many subjective outcomes, some of which are surrogates, increases the likelihood of detecting a statistically significant but spurious benefit from treatment. The need for randomised, double blind, controlled studies, as far as possible with objective outcomes, is clear. In some settings a “no treatment” control is crucially important. 

The authors explore the lack of credibility of treatments such as homoeopathy among bioscientists and orthodox physicians. They examine two recent reviews of homoeopathy trials, noting that some trials compared homoeopathy with placebo and others with a standard treatment, and that many different diseases were reviewed together. Meta-analysis cannot resolve such lack of homogeneity, so a large, double blind, randomised controlled trial is the compelling answer. Is such a study worth while? The authors believe so, but difficulties remain. I think a homoeopathy trial should contain both an “inactive placebo” group and a “no treatment” group. No such study has been published. 

The few audits of injury from complementary medicine suggest that severe complications are mainly associated with acupuncture (such as pneumothorax and systemic infection) and manipulation (such as vertebral artery dissection). Reports on reactions to herbalism mostly describe contamination of herbal mixtures by toxic heavy metals. The public and professionals handle herbal medicines much less carefully than they do orthodox drugs. 

We need much more, and better, information on the adverse reactions to complementary treatments. We can obtain evidence from randomised controlled trials of their effectiveness compared with no treatment, with appropriate placebo, and with standard orthodox treatment. Without reliable information, we cannot decide which alternative treatments are both effective and reasonably safe.