Strain-specific and outcome-specific efficacy of probiotics for the treatment of irritable bowel syndrome: A systematic review and meta-analysis

Background: Consistent guidance for choosing an appropriate probiotic for the treatment of irritable bowel syndrome is lacking. Methods: Literature databases searched included: PubMed, Google Scholar and NIH registry of clinical trials from inception to June 2021. Inclusion criteria: randomized controlled trials (RCTs) enrolling adult or pediatric IBS patients comparing probiotics against controls and >= 2 RCTs with common IBS outcome measures within each type of probiotic. Five common measures of IBS symptoms (changes in global Irritable Bowel Syndrome Severity Scoring System or IBS-SSS scores, frequency of global responders, changes in bloating or abdominal pain scores and frequency of abdominal pain relief) were used. This study was registered at Prospero (#CRD42018109169). Findings: We screened 521 studies and included 42 randomized controlled trials (45 treatment arms, N = 3856). Four probiotics demonstrated significant reduction in abdominal pain relief: B. coagulans MTCC5260 (RR= 4.9, 95% C.I. 3.3, 7.3), L. plantarum 299v (RR= 4.6, 95% CI 1.9, 11.0), S. boulardii CNCM I-745 (RR= 1.5, 95% C.I. 1.1, 2.1) and S. cerevisiae CNCM I-3856 (RR= 1.3, 95% C.I. 1.04, 1.6). Mild-moderate adverse events were reported in 51% of the trials, none were more associated with the probiotic compared to controls. Interpretation: Although the analysis of probiotic efficacy was limited by the diversity of IBS outcomes used in trials and lack of confirmatory trials for some strains, six single-strain probiotics and three different types of probiotic mixtures showed significant efficacy for at least one IBS outcome measure. These results might be relevant to clinical practice and policy. (C) 2021 The Author(s). Published by Elsevier Ltd.