ABSTRACT
Complementary Therapies in Neurology: An Evidence-Based Approach Edited by Barry S.Oken ISBN 1-84214-200-3 Copyright © 2004 by The Parthenon Publishing Group, London
INTRODUCTION
‘Placebo’ and ‘placebo effect’ are terms that have multiple meanings and connotations and have had a varied history over the past 50 years1-3. The terms may not beideal, because of negative associations, but the terms are in widespread use with several books on the topic2,4,5. There is an effect on subjective or biomarker outcomes in many clinical interactions, including clinical trials, owing to a substance or procedure for which we do not expect there to be a direct biological effect on the underlying primary pathophysiology. These indirect or non-specific effects of biologically inert substances or inactive procedures come under the general term placebo effects. It is likely that much improvement in patients following an encounter with a health-care provider is mediated via fairly indirect mechanisms and not at the specific underlying pathophysiology of the disease the patient may have. Some have suggested that much of the improvement patients experience following encounters with complementary health-care providers is related to the placebo effect, but the same could be said for patients seen by conventional medical providers6. The placebo issue is particularly problematic in complementary medicine, because of the frequent lack of patient blinding with some complementary therapy studies7. Although placebo effects contribute to variability in outcome data that are at least partially independent of known direct biological effects of the interventions, simply considering placebo as noise or confounding in clinical trials is not helpful in understanding the mechanisms.
