Efficacy and safety of fecal microbiota transplantation for the induction of remission in active ulcerative colitis: a systematic review and meta-analysis of randomized controlled trials.

Background: Fecal microbiota transplantation (FMT) is a novel management strategy for ulcerative colitis (UC). However, its effectiveness remains controversial. This study sought to assess the effectiveness of FMT in the treatment of active UC by performing a meta-analysis of randomized controlled trials (RCTs). Methods: We searched the Cochrane, Embase, PubMed, and Web of Science databases from their inception to December 2021. RCTs that recruited patients with active UC and treated them with FMT, a placebo or a suitable comparator were included in the meta-analysis. PICOS: Patients, active UC; Intervention, FMT; Control, placebo or a suitable comparator; Outcomes, remission rate; Studies, RCTs. The risk of bias assessment was performed with Revised Cochrane risk-of-bias tool (version 2). Meta-analyses of risk ratios (RRs) were performed to estimate the differences in remission rates and the risk of serious adverse events (SAEs) between the FMT-treated and control patients. Results: A total of 9 RCTs comprising 425 UC patients (213 FMT and 212 control) were included in the meta-analysis. The risk of bias was low in these RCTs. Clinical remission was observed in 86 of the 213 patients in the FMT groups and 47 of the 212 patients in the control groups [RR: 1.84; 95% confidence interval (CI): 1.37, 2.47; P<0.0001]. Clinical remission was better when the FMT delivery route was via the lower gut, the FMT dose was >300 grams, and the fecal specimen from multiple donors. Endoscopic remission (observed in 7 RCTs) was achieved in 33 of the 195 FMT-treated patients compared to 17 of the 194 control patients (RR: 1.94; 95% CI: 1.14, 3.31; P=0.01). SAEs were reported in 22 of the 213 FMT-treated patients but only 11 of the 212 control patients (RR: 2.05; 95% CI: 1.03, 4.09; P=0.04). Discussion: FMT is an effective treatment for patients with active UC. Significantly higher clinical and endoscopic remission rates are observed with FMT than with control treatments. However, FMT may cause a significantly higher incidence of SAEs than control treatments. Future studies should delineate the effects of donor selection, dosage, delivery route, and antibiotic pretreatment and should evaluate the safety profile of FMT.