Does Inflammatory Bowel Disease Activity Alter Following Liver Transplantation? A Systematic Review an‎d Meta-Analysis Protocol

Inflammatory bowel disease (IBD) is associated with primary sclerosing cholangitis (PSC), an uncommon chronic and progressive cholestatic liver disease. Liver transplantation (LT) is the only therapeutic strategy for PSC that may also affect the IBD course. Considering the lack of systematic reviews and pursuing debates on this issue, we aim to systematically assess the frequencies of patients with an improved, unchanged, or exacerbated IBD course following LT and to conduct a meta-analysis. Methods: In this systematic review, PubMed/MEDLINE, Scopus, WoS (Clarivate Analytics), and Embase will be searched. Our search strategy (i.e., the eligibility criteria) covers prospective and retrospective observational studies evaluating the clinical course of ulcerative colitis or Crohn’s disease after LT, with no language limitation, published between 01/01/1970 and 30/12/2020. Two authors will independently implement the selection phase, data extraction, and quality assessment. In case of any disagreement between the authors, the issue will be resolved by consensus; if not resolved, the opinion of a third expert will be asked. If there are sufficient studies, the pooled frequencies (%) of patients with improved, unchanged, or exacerbated IBD activity following LT will be calculated using random or fixed effect models according to severity of methodological heterogeneity. Forest plots will show the separated and combined frequencies and the corresponding 95% CIs. The Q-statistic test and I2 statistics will be used to evaluate statistical heterogeneity. We will use the funnel plot technique to assess reporting bias and Begg’s and Egger’s tests for publication bias. The trim and fill method will correct the effect of any potential publication bias. Ethics and Dissemination: As this review will use published primary studies, an ethics committee review is not necessary. The results of our research will be published in peer-review journals and presented in relevant conference meetings.