J Neurogastroenterol Motil.  2014 Apr;20(2):163-170.

Placebo Effect in Clinical Trial Design for Irritable Bowel Syndrome

• Shah E
• Pimentel M

Abstract

Ongoing efforts to improve clinical trial design in irritable bowel syndrome have been hindered by high placebo response rates and ineffective outcome measures. We assessed established strategies to minimize placebo effect as well as the various approaches to placebo effect which can affect trial design. These include genetic markers such as catechol-O-methyltransferase, opioidergic and dopaminergic neurobiologic theory, pre-cebo effect centered on expectancy theory, and side effect unblinding grounded on conditioning theory. We reviewed endpoints used in the study of IBS over the past decade including adequate relief and subjective global relief, emphasizing their weaknesses in fully evaluating the IBS condition, specifically their motility effects based on functional net value and relative benefit-harm based on dropouts due to adverse events. The focus of this review is to highlight ongoing efforts to improve clinical trial design which can lead to better outcomes in a real-world setting.

Keyword

Clinical trial; Irritable bowel syndrome; Placebos

MeSH Terms

Catechol O-Methyltransferase
Genetic Markers
Humans
Irritable Bowel Syndrome*
Outcome Assessment (Health Care)
Patient Dropouts
Placebo Effect*
Placebos
Catechol O-Methyltransferase
Genetic Markers
Placebos