The Effect of Placebo in Irritable Bowel Syndrome and Functional Constipation in Children: A Systematic Review

Review Article

The Effect of Placebo in Irritable Bowel Syndrome and Functional Constipation in Children: A Systematic Review

Merit M Tabbers¹, Arnold GE Leenders² and Marc A Benninga¹

Affiliations: ¹Department of Pediatric Gastroenterology and Nutrition, Emma Children’s Hospital and ²Medical Library, Academic Medical Center, Amsterdam, the Netherlands

ABSTRACT

Aim
Placebo effect has an important impact on the interpretation of randomized controlled trials (RCTs) in children with functional gastrointestinal disorders. This article gives an overview of the current evidence for placebo use in the treatment of children with irritable bowel syndrome (IBS) and functional constipation.

Methods
We performed a systematic literature search in Pubmed, Embase, CINAHL, and Cochrane Library databases, and included systematic reviews and RCTs concerning placebo treatment in children with IBS and functional constipation.

Results
Two systematic reviews and two subsequent RCTs were found in children with IBS. These studies showed that Lactobacillus GG was more effective than placebo with respect to reduction in pain frequency and decrease in perceived abdominal distension. Compared with placebo, peppermint oil seemed to be more effective in improving symptoms related to IBS. Placebo and amitriptyline were equally effective in response to treatment (child’s assessment of pain relief and sense of improvement) in children with IBS. In a small RCT, however, amitriptyline was more effective than placebo in improvement in the overall quality of life score in children with IBS. Only two systematic reviews were found in children with functional constipation, reporting that fiber may be more effective than placebo in improving bowel movements, in improvement of stool consistency, and in the reduction of abdominal pain. Macrogol was more effective than placebo in increasing the number of defecations, reduction of hard stools, and in reduction of pain and straining during defecation.


CONCLUSION

There is a lack of placebo‐controlled trials of high quality in children with IBS and functional constipation. More well‐designed, large RCTs are necessary to determine and understand the role of placebo in children with these functional gastrointestinal disorders.

Keywords: placebo, children, review, randomized controlled trial, functional gastrointestinal disorders, irritable bowel syndrome, functional constipation

Correspondence: M M Tabbers, Department of Pediatric Gastroenterology and Nutrition, Room G8‐216‐1, Emma Children’s Hospital/Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, the Netherlands. Tel: (31)‐20‐5663053; Fax: (31)‐20‐6917735; e‐mail: m.m.tabbers@amc.nl