CRD summary

This review evaluated efficacy, safety and tolerability of probiotics in irritable bowel syndrome and concluded that Bifidobacteriuminfantis 35624 showed efficacy in improving symptoms; data for other probiotics were inadequate. The conclusion that evidence on probiotics was of poor quality appeared appropriate, although conclusions about the efficacy of B. infantis may be less reliable.

Authors' objectives

To evaluate efficacy, safety and tolerability of probiotics in treatment of irritable bowel syndrome (IBS).

Searching

MEDLINE, PubMed, EMBASE and The Cochrane Library were searched from inception to June 2008 to identify relevant articles published in English. Search terms were reported. Abstracts from Digestive Disease Week, annual meeting of American College of Gastroenterology and United European Gastroenterology Week were searched from 2001 to 2007. Reference lists of retrieved studies and relevant reviews and guidelines were searched.

Study selection

Randomised placebo-controlled trials (RCTs) that evaluated single or combination probiotics in patients with IBS (defined by Manning or Rome II criteria) and that reported IBS symptoms, adverse events or tolerability were eligible for inclusion in the review.

Included studies evaluated 13 different probiotics or combinations of probiotics. Where reported, mean age of patients who received probiotics ranged from 38 to 51 years and the proportion of female patients ranged from 56% to 100%

Two reviewers independently selected studies for inclusion. Disagreements were resolved by consensus.

Assessment of study quality

The validity of studies was assessed using the Rome II methodology scale (studies receive up to 14 points for trial design).

The authors did not state how many reviewers performed the assessment.

Data extraction

The authors directly extracted outcome data from the included studies, but did not state how many reviewers performed the extraction.

Methods of synthesis

Studies were combined in a narrative synthesis grouped by probiotic.

Results of the review

Sixteen RCTs (n=1,342) met the inclusion criteria. Studies scored between 5 and 12 points on the Rome II methodology scale. Eleven studies were considered to be of suboptimal design (precise definition of suboptimal was not clear).

Two of the appropriately-designed RCTs evaluated Bifidobacterium infantis 35624 and reported statistically significant improvements in abdominal pain/discomfort, bloating/distension and/or bowel movement relative to placebo (p<0.05). In these two trials B. infantis 35624 was given daily for four or eight weeks as 1x10¹⁰ live cells in malted milk drink or 1x10⁶, 1x10⁸ or 1x10¹⁰ colony forming units per millilitre in capsule form. None of the other studies described as appropriately designed showed significant improvements in IBS symptoms.

No studies reported quantifiable data on relative tolerability or adverse events.

Authors' conclusions

B. infantis 35624 showed efficacy in terms of improvement in IBS symptoms. There were inadequate data on efficacy or adverse effects of other probiotics in IBS.

CRD commentary

The review was based on a question clearly defined in terms of the participants, interventions, controls, outcomes and study designs of interest. Several electronic and other sources were searched for relevant articles. Limiting the search to published English-language studies meant that language and publication biases could not be ruled out. Attempts were made to minimise potential for errors and bias in study selection; it was unclear whether this was the case for other review processes. Validity of included studies was assessed using an established method, although the threshold at which studies were considered to be of adequate quality was unclear and there may be potential for bias in this process. The authors conclusion that most of the evidence for probiotics was of inadequate quality appeared appropriate; their specific conclusion about efficacy of B. infantis may be less reliable.

Implications of the review for practice and research

The authors did not make any recommendations for practice.

Research: The authors stated that further studies of probiotics other than B. infantis were needed and these should adhere to the Rome III guidelines on the design of gastrointestinal disorder trials. They added that further studies to assess longevity of response were needed.

Funding

None stated.

Bibliographic details

Brenner DM, Moeller MJ, Chey WD, Schoenfeld PS. The utility of probiotics in the treatment of irritable bowel syndrome: a systematic review. American Journal of Gastroenterology 2009; 104(4): 1033-1049. [PubMed: 19277023]

Original Paper URL

http://www.nature.com/ajg/journal/v104/n4/abs/ajg200925a.html

Indexing Status

Subject indexing assigned by NLM

MeSH

Bifidobacterium; Humans; Irritable Bowel Syndrome /drug therapy; Probiotics /therapeutic use; Treatment Outcome

AccessionNumber

12009105264

Database entry date

31/03/2010

Record Status

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.