Fecal Microbiota Transplantation (FMT) and Clinical Outcomes among Inflammatory Bowel Disease (IBD) Patients: An Umbrella Review

Background and Aims: Recent systematic reviews and meta-analyses (SRMAs) have shown inconsistent effectiveness of FMT among IBD patients. This study aimed to appraise the evidence for clinically relevant outcomes with FMT in IBD patients using published SRMAs. Methods: We searched major databases from inception through Nov 2023 to identify SRMAs assessing the effectiveness of FMT in IBD patients. Primary outcomes included clinical remission, clinical response, endoscopic remission/response, a composite endpoint, and adverse effects. We included SRMAs investigating FMT's effect in IBD patients using RCTs and observational studies data. Methodological quality and evidence certainty were assessed using AMSTAR 2 and GRADE. Results: Out of 106 citations, 16 SRMAs were included with varying study sizes (2 to 60 primary studies) and participants (112 to 1169 per SRMA). Five SRMAs assessed FMT in IBD, while 11 focused on Ulcerative Colitis (UC). Seven SRMAs included RCTs only, and nine included both RCTs and observational studies. Methodological quality was critically low in 9 SRMAs (56%) and low in 7 studies (44%). FMT showed clinical remission benefit in all 16 SRMAs, with varying certainty: 3 high, 4 moderate, 4 low, and 5 very low. Endoscopic remission/response was reported in 5 meta-analyses on UC, with 1 high, 3 moderate, and 1 very low certainty. Combined clinical remission and endoscopic response were reported in 3 SRMAs on UC, with 1 low and 2 moderate certainty. Adverse events were reported in 6 SRMAs, with 1 high, 3 moderate, 1 low, and 1 very low certainty. Conclusion: Current evidence shows potential benefits of FMT in IBD, particularly UC, supported by significant associations in 16 meta-analyses. However, poor methodological quality and variability in evidence certainty call for high-quality RCTs to strengthen the evidence.