Published online Mar 14, 2015. doi: 10.3748/wjg.v21.i10.3072
Peer-review started: June 4, 2014
First decision: July 9, 2014
Revised: July 24, 2014
Accepted: September 29, 2014
Article in press: September 30, 2014
Published online: March 14, 2015
AIM: To investigate the efficacy of probiotics in irritable bowel syndrome (IBS) patients.
METHODS: PubMed, Cochrane library, Scopus, Google Scholar, and Clinicaltrial.gov databases were searched for literature published between September 2007 and December 2013. The applied Mesh terms were “probiotics,”“irritable bowel syndrome,” and “irritable bowel syndrome treatment.” The collected data contained24 clinical trials, of which 15 were eligible for meta-analysis and nine were reviewed systematically. All studies were randomized placebo-controlled trials in patients with IBS that investigated the efficacy of probiotics in IBS improvement. The Jadad score was used to assess the methodological quality of trials. The quality scale ranges from 0 to 5 points, with a score ≤ 2 indicating a low quality report, and a score of ≥ 3 indicating a high quality report. Relative risk (RR), standardized effect size, and 95%CI were calculated using the DerSimonian-Laird method. The Cochran Q test was used to test heterogeneity with P < 0.05. Funnel plots were constructed and Egger’s and Begg-Mazumdar tests were performed to assess publication bias.
RESULTS: A total of 1793 patients were included in the meta-analysis. The RR of responders to therapies based on abdominal pain score in IBS patients for two included trials comparing probiotics to placebo was 1.96 (95%CI: 1.14-3.36; P = 0.01). RR of responders to therapies based on a global symptom score in IBS patients for two included trials comparing probiotics with placebo was 2.43 (95%CI: 1.13-5.21; P = 0.02). For adequate improvement of general symptoms in IBS patients, the RR of seven included trials (six studies) comparing probiotics with placebo was 2.14 (95%CI: 1.08-4.26; P = 0.03). Distension, bloating, and flatulence were evaluated using an IBS severity scoring system in three trials (two studies) to compare the effect of probiotic therapy in IBS patients with placebo, the standardized effect size of mean differences for probiotics therapy was -2.57 (95%CI: -13.05--7.92).
CONCLUSION: Probiotics reduce pain and symptom severity scores. The results demonstrate the beneficial effects of probiotics in IBS patients in comparison with placebo.
Core tip: Irritable bowel syndrome (IBS) is a gastrointestinal tract dysfunction with a complicated etiology. Probiotics may influence IBS symptoms. The present meta-analysis included 1793 patients with all subtypes of IBS from 15 randomized, double-blind clinical trials conducted during 2007-2013. The current and previous meta-analyses are mainly limited by the use of different scales to analyze the mean differences of symptoms among various studies. Thus, further clinical trials are still needed to conclude the effectiveness of probiotics on specific major IBS symptoms of patients. Probiotics may have a beneficial therapeutic role in IBS patients.