Gut microbiome-targeted therapies as adjuvant treatments in inflammatory bowel diseases: a systematic review and network meta-analysis

Background and aim: Gut microbiome-targeted therapies (MTTs), including prebiotics, probiotics, synbiotics, and fecal microbiota transplantation (FMT), have been widely used in inflammatory bowel diseases (IBD), but the best MTTs has not yet been confirmed. We performed a network meta-analysis (NMA) to examine this in ulcerative colitis (UC) and Crohn's disease (CD).

Methods: We searched for randomized controlled trials (RCTs) on the efficacy and safety of MTTs as adjuvant therapies for IBD until December 10, 2023. Data were pooled using a random effects model, with efficacy reported as pooled relative risks with 95% CIs, and interventions ranked according to means of surfaces under cumulative ranking values.

Results: Thirty-eight RCTs met the inclusion criteria. Firstly, we compared the efficacy of MTTs in IBD patients. Only FMT and probiotics were superior to placebo in all outcomes, but FMT ranked best in improving clinical response rate and clinical and endoscopic remission rate, and probiotics ranked second in reducing clinical relapse rate showed significant efficacy, while prebiotics ranked first showed nonsignificant efficacy. Subsequently, we conducted NMA for specific MTT formulations in UC and CD separately, which revealed that FMT, especially combined FMT via colonoscopy and enema, showed significant efficacy and was superior in improving clinical response and remission rate of active UC patients. As for endoscopic remission and clinical relapse, multistrain probiotics based on specific genera of Lactobacillus and Bifidobacterium showed significant efficacy and ranked best in UC. In CD, we found that no MTTs were significantly better than placebo, but synbiotics comprising Bifidobacterium and fructo-oligosaccharide/inulin mix and Saccharomyces ranked best in improving clinical remission and reducing clinical relapse, respectively. Moreover, FMT was safe in both UC and CD.

Conclusions: FMT and multistrain probiotics showed superior efficacy in UC. However, the efficacy of MTTs varies among different IBD subtypes and disease stages; thus, the personalized treatment strategies of MTTs are necessary.