The placebo effect for gastroenterology: tool or torment.

Placebo generally has a negative connotation both in clinical practice and in clinical trials. In this report the nature of placebo is explored in general and in relation to gastrointestinal diseases. The goodness of placebo is highlighted. PubMed was searched for articles and commentaries on placebo and for systematic reviews on placebo. Selected placebo-controlled trials in gastroenterology were reviewed. There are 5 key components impacting the placebo response: patient characteristics, practitioner characteristics, practitioner-patient interaction, the nature of the illness being treated, and the treatment being applied and the setting in which it is applied. There are also a number of factors that constitute the placebo response and likely all apply to some extent. These include the natural history of the condition, a regression to the mean (accounting for fluctuation in measurements over time), other time effects (ie, patient learning to cope, practitioner gaining expertise), unidentified parallel interventions (ie, change in habits or exogenous stress), the placebo effect of the administered agent being compared with placebo, and the physiologic effects of the placebo. In summary, there are positive aspects to placebo. Clinicians treating patients with gastrointestinal diseases can harness aspects of the placebo response to improve patient outcomes. Clinical trial planners can harness aspects of the placebo response to design disease-specific trials that can minimize the placebo response.