Ein methodenkrititscher Überblick zu Placeboeffekten unter besonderer Berücksichtigung von gastrointestinalen Erkrankungen

Abstract

Background: In its classical definition a placebo is considered to be a substrate free medication surrogate that induces positive effects on a disease when given to a patient. The effect is then not attributable to a specific active agent of the placebo. This placebo concept has always been associated with a negative connotation and was interpreted as deception and withholding of an effectice treatment. Due to enhanced research on placebo effects and the assumption that some aspects of verum treatment effects are as well attributable to a so-called placebo effect, the actual discussion on placebo turns towards the utilization of placebo effects in clinical practice.

Placebo effects are common in gastrointestinal disorders, while the size of these placebo effects is not related to the functional aspects of the disease. Placebo effects in functional dyspepsia and irritable bowel syndrome are as high as in organic gastrointestinal diseases such as duodenal ulcer or inflammatory bowel disease.

Conclusion: In many aspects, placebo effects are not distinguishable from the effects of other interventions including pharmacological treatments. Thus, a strengthening of a verum treatment by placebo induced factors has the potential to optimize a treatment. However, especially in the older placebo literature the effect sizes of placebo effects were overestimated. This was mainly due to methodological deficiencies of former studies. The presented article gives an overview about criticism on methodologies of these studies, with a focus on research results of gastroenterology.