Resolution rates in clinical trials for microbiota restoration for recurrent Clostridioides difficile infection: an updated systematic review and meta-analysis

BACKGROUND: Microbiota restoration is highly effective to treat recurrent Clostridioides difficile infection (CDI) in observational studies (cure rates >90%) but efficacy in controlled clinical trials appears to be lower. OBJECTIVES: To perform an updated meta-analysis to assess the efficacy of microbiota restoration for recurrent CDI in open-label registered prospective clinical trials compared to randomized controlled trials (RCTs). DESIGN: A systematic review and meta-analysis was conducted. DATA SOURCES AND METHODS: A systematic search of various databases was performed up to July 2022 to identify studies of interest. Clinical trials of microbiota restoration for recurrent CDI with clinical resolution with one dose were included. We calculated weighted pooled rates (WPRs) with 95% confidence intervals (CIs). RESULTS: In all, 19 clinical trials with 1176 recurrent CDI patients were included. Of the patients treated with microbiota restoration, 897 experienced a clinical cure with a single microbiota restoration therapy (WPR, 78%; 95% CI, 71–85%). There was significant heterogeneity among studies with an I(2) of 88%. Analysis of trials with a control arm (non-microbiota restoration) revealed CDI resolution in 373 of 523 patients (WPR, 72%; 95% CI, 60–82%) with microbiota restoration. Among the nine open-label clinical trials, CDI resolution was seen in 524 of 653 patients after initial microbiota restoration (WPR, 84%; 95% CI, 74–92%). Comparison of resolution rates between RCTs and open-label trials revealed a lower cure rate in RCTs compared to open-label trials (WPR, 73 versus 84%, p < 0.0001). CONCLUSIONS: Microbiota restoration in a randomized controlled setting leads to lower resolution rates compared to open label and observational settings, likely due to stricter definitions and inclusion criteria. Resolution rates in open-label studies were similar to observational studies.