Efficacy and safety of probiotics in IBD: An overview of systematic reviews and updated meta-analysis of randomized controlled trials.

Background and objective: Probiotics show promise in inflammatory bowel disease (IBD), yet knowledge gaps persist. We performed an overview of systematic reviews and an updated metanalysis of randomized controlled trials (RCT) assessing the effect of probiotics on Crohn's disease (CD) and ulcerative colitis (UC).

Methods: MEDLINE, Web of Science, and the Cochrane Central Register of Controlled Trials were searched up to September 2023. Primary outcomes were clinical remission and recurrence; secondary outcomes included endoscopic response and remission, and adverse events. We calculated odds ratios (OR) using a random-effects model in R. The quality of systematic reviews was assessed using the AMSTAR-2; the trials' risk of bias was evaluated using the Cochrane Collaboration tool. Evidence certainty was rated using the GRADE framework.

Results: Out of 2613 results, 67 studies (22 systematic reviews and 45 RCTs) met the eligibility criteria. In the updated meta-analysis, the OR for clinical remission in UC and CD was 2.00 (95% CI 1.28-3.11) and 1.61 (95% CI 0.21-12.50), respectively. The subgroup analysis suggested that combining 5-ASA and probiotics may be beneficial for inducing remission in mild-to-moderate UC (OR 2.35, 95% CI 1.29-4.28). Probiotics decreased the odds of recurrence in relapsing pouchitis (OR 0.03, 95% CI 0.00-0.25) and trended toward reducing clinical recurrence in inactive UC (OR 0.65, 95% CI 0.42-1.01). No protective effect against recurrence was identified for CD. Multi-strain formulations appear superior in achieving remission and preventing recurrence in UC. The use of probiotics was not associated with better endoscopic outcomes. Adverse events were similar to control. However, the overall certainty of evidence was low.

Conclusion: Probiotics, particularly multi-strain formulations, appear efficacious for the induction of clinical remission and the prevention of relapse in UC patients as well as for relapsing pouchitis. Notwithstanding, no significant effect was identified for CD. The favorable safety profile of probiotics was also highlighted.