title: Effectiveness of probiotics in irritable bowel syndrome: Updated systematic review with meta-analysis.
abstract: OBJECTIVE
  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).
  
  
  CONCLUSIONS
  Probiotics reduce pain and symptom severity scores. The results demonstrate the beneficial effects of probiotics in IBS patients in comparison with placebo.
authors.affiliation: Tina Didari, Shilan Mozaffari, Mohammad Abdollahi, Department of Toxicology and Pharmacology, Faculty of Pharmacy and Pharmaceutical Sciences Research Center, Tehran University of Medical Sciences, Tehran 1417614411, Iran.
authors.forename: Tina
authors.initials: T
authors.lastname: Didari
authors.affiliation: Tina Didari, Shilan Mozaffari, Mohammad Abdollahi, Department of Toxicology and Pharmacology, Faculty of Pharmacy and Pharmaceutical Sciences Research Center, Tehran University of Medical Sciences, Tehran 1417614411, Iran.
authors.forename: Shilan
authors.initials: S
authors.lastname: Mozaffari
authors.affiliation: Tina Didari, Shilan Mozaffari, Mohammad Abdollahi, Department of Toxicology and Pharmacology, Faculty of Pharmacy and Pharmaceutical Sciences Research Center, Tehran University of Medical Sciences, Tehran 1417614411, Iran.
authors.forename: Shekoufeh
authors.initials: S
authors.lastname: Nikfar
authors.affiliation: Tina Didari, Shilan Mozaffari, Mohammad Abdollahi, Department of Toxicology and Pharmacology, Faculty of Pharmacy and Pharmaceutical Sciences Research Center, Tehran University of Medical Sciences, Tehran 1417614411, Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Abdollahi
mesh_terms: D015746:Abdominal Pain / Q000175:diagnosis / Q000382:microbiology / Q000628:therapy; D005414:Flatulence / Q000382:microbiology / Q000628:therapy; D006801:Humans; D007422:Intestines / Q000382:microbiology* / Q000503:physiopathology; D043183:Irritable Bowel Syndrome / Q000175:diagnosis / Q000382:microbiology / Q000503:physiopathology / Q000628:therapy*; D016017:Odds Ratio; D010147:Pain Measurement; D019936:Probiotics / Q000009:adverse effects / Q000627:therapeutic use*; D011788:Quality of Life; D020127:Recovery of Function; D012720:Severity of Illness Index; D016896:Treatment Outcome
keywords: Clinical trial; Evidence-based medicine; Irritable bowel syndrome; Meta-analysis; Probiotics; Systematic review