TBA (25W166)

Diagnostic Transition from Ulcerative Colitis to Crohn’s Disease in Pouch Patients: Clinical Outcomes and Treatment Needs.

Author(s)

M Nwaezeigwe, J Sheridan, G Doherty, S Martin, G Cullen.

Department(s)/Institutions

Dept. of Gastroenterology, St Vincents University Hospital. Dublin.

Introduction

Crohn’s disease of the pouch (CDP) is a leading cause of pouch dysfunction and failure. While meta-analyses suggest up to 10% of patients develop CDP following pouch surgery for ulcerative colitis (UC), long-term outcome data remain limited.

Aims/Background

To assess the natural history, treatment course, and pouch survival in patients reclassified as Crohn’s disease after ileal pouch–anal anastomosis (IPAA) compared with those with confirmed UC.

Method

We conducted a retrospective cohort study of patients who underwent IPAA between 1991–2016, with follow-up data available from 2012 onwards. Patients reclassified as Crohn’s disease were compared with those retaining a UC diagnosis to evaluate outcomes.

Results

120 UC patients (64% male; median age 51 years) with primary IPAA were included. At a median follow-up of 9 years, 25 patients (20%) were reclassified as Crohn’s disease. Reclassification was most commonly driven by prepouch ileitis and/or ileal ulceration (60%), followed by fistula (44%), stricture (32%), and perineal abscess (12%), alone or in combination. Two patients had histological confirmation of Crohn’s disease postoperatively. Among CDP patients, 84% required biologic therapy, with more than one-third needing sequential biologics. Pouch excision occurred in 16% of CDP patients compared with 6% of UC patients (OR 2.8, 95% CI 0.73–10.9, p=0.21).

Conclusions

CDP was more frequent in our cohort and associated with greater biologic use and higher rates of pouch excision. Although the risk of pouch failure was higher in CDP, this did not reach statistical significance, likely due to limited sample size. These findings highlight the complex disease course and management challenges in this group compared to UC pouchitis.