The Natural History After Ileal Pouch-Anal Anastomosis for Ulcerative Colitis: A Population-Based Cohort Study From the United States.

Introduction: There are limited data regarding the natural history after ileal pouch-anal anastomosis (IPAA) for ulcerative colitis (UC). The principal objectives of this study were to identify 4 key outcomes in the natural history after IPAA within 1, 3, 5, and 10 years: the incidence of pouchitis, Crohn's-like disease of the pouch, use of advanced therapies after IPAA, and pouch failure requiring excision in a network of electronic health records.

Methods: We performed a retrospective cohort study in TriNetX, a research network of electronic health records. In addition to evaluating incidence rates, we also sought to identify factors associated with pouchitis and advanced therapy use within 5 years of IPAA after 1:1 propensity score matching, expressed as adjusted hazard ratios (aHRs).

Results: Among 1,331 patients who underwent colectomy with IPAA for UC, the incidence of pouchitis increased from 58% in the first year after IPAA to 72% at 10 years after IPAA. After propensity score matching, nicotine dependence (aHR 1.61, 95% confidence interval [CI] 1.19-2.18), antitumor necrosis factor therapy (aHR 1.33, 95% CI 1.13-1.56), and vedolizumab prior to colectomy (aHR 1.44, 95% CI 1.06-1.96) were associated with an increased risk of pouchitis in the first 5 years after IPAA. The incidence of Crohn's-like disease of the pouch increased to 10.3% within 10 years of IPAA while pouch failure increased to 4.1%. The incidence of advanced therapy use peaked at 14.4% at 10 years after IPAA.

Discussion: The incidence of inflammatory conditions of the pouch remains high in the current era, with 14% of patients requiring advanced therapies after IPAA.