Systematic Reviews
Copyright ©The Author(s) 2017. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Mar 28, 2017; 23(12): 2223-2233
Published online Mar 28, 2017. doi: 10.3748/wjg.v23.i12.2223
Systematic review: The placebo effect of psychological interventions in the treatment of irritable bowel syndrome
Carla E Flik, Laura Bakker, Wijnand Laan, Yanda R van Rood, André J P M Smout, Niek J de Wit
Carla E Flik, Laura Bakker, Wijnand Laan, Niek J de Wit, Department of General Practice, Julius Centre for Health Sciences and Primary Care, University Medical Centre Utrecht, 3508GA Utrecht, The Netherlands
Carla E Flik, Department of Psychiatry and Psychology, St Antonius Hospital, 3435CM Nieuwegein, The Netherlands
Yanda R van Rood, Department of Psychiatry, University Medical Centre, 2333ZA Leiden, The Netherlands
André J P M Smout, Department of Gastroenterology and Hepatology, Academic Medical Centre, 1105AZ Amsterdam, The Netherlands
Author contributions: Flik CE, Bakker L and de Wit NJ designed the study; Flik CE, Bakker L and Laan W analyzed the data and performed the calculations; Flik CE, Bakker L, Laan W and van Rood YR wrote the article in discussion with Smout AJPM and de Wit NJ, especially van Rood YR; Smout AJPM and de Wit NJ gave suggestions to improve the text and all authors contributed to the discussion of the data; all authors approved the final version of the manuscript.
Conflict-of-interest statement: None of the authors has any conflict of interest.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Correspondence to: Dr. Carla E Flik, Department of General Practice, Julius Centre for Health Sciences and Primary Care, University Medical Centre Utrecht, Str. 6.131, P.O. Box 85500, 3508 GA Utrecht, The Netherlands.
Telephone: +31-88-7568355 Fax: +31-88-7568355
Received: June 24, 2016
Peer-review started: June 29, 2016
First decision: August 29, 2016
Revised: October 10, 2016
Accepted: November 15, 2016
Article in press: November 15, 2016
Published online: March 28, 2017

To determine the placebo response rate associated with different types of placebo interventions used in psychological intervention studies for irritable bowel syndrome.


Randomized controlled trials comparing psychological interventions (stress management/relaxation therapy (cognitive) behavioral therapy, short-term psychodynamic therapy, and hypnotherapy) for the treatment of adult patients with irritable bowel syndrome (IBS) diagnosed with the Manning or Rome criteria with an adequate placebo control treatment and reporting data on IBS symptom severity were identified by searching PubMed, Embase, the Cochrane Library, CINAHL and PsycINFO databases. Full-text articles that were written in English and published between 1966 and February 2016 in peer-reviewed journals were selected for the present review. Placebo interventions were considered to be adequate if the number of sessions and the amount of time spent with the therapist were the same as in the active treatment. The placebo response rate (PRR) was computed for IBS symptom severity (primary outcome measure) as well as for anxiety, depression and quality of life (secondary outcome measures).


Six studies, with a total of 555 patients met the inclusion criteria. Four studies used an educational intervention, whereas two studies used a form of supportive therapy as the placebo intervention. The PRR for IBS symptom severity ranged from 25% to 59%, with a pooled mean of 41.4%. The relative PRR for the secondary outcome measures ranged from 0% to 267% for anxiety, 6% to 52% for depression 20% to 125% for quality of life. The PRR associated with pharmacological treatments, treatment with dietary bran and complementary medicine ranged from 37.5% to 47%. Contrary to our expectations, the PRR in studies on psychological interventions was comparable to that in studies on pharmacological, dietary and alternative medical interventions.


The PRR is probably determined to a larger extent by patient-related factors, such as expectations and desire for the treatment to be effective, than the content of the placebo intervention.

Keywords: Placebo effect, Psychological interventions, Irritable bowel syndrome, Systematic review

Core tip: This study highlights the fact that providing patients with realistic, but positive information about the expected effect of the treatment for irritable bowel syndrome is important to optimize the placebo response.