Abstract
AIM: Tumour necrosis factor inhibitors (TNFi) have revolutionized the management of moderate to severe ulcerative colitis (UC) since their approval for UC in 2005. However, many patients ultimately require surgery with ileal pouch-anal anastomosis (IPAA). Development of de novo Crohn's disease (CD) following IPAA is an increasingly common and devastating complication, sometimes progressing to pouch failure. The aim of this study was to evaluate the association of preoperative TNFi exposure and the development of de novo CD after IPAA. METHOD: A prospective single-centre inflammatory bowel disease (IBD) registry was searched for consecutive patients with UC undergoing IPAA during a 25-year period ending July 2018. Patients with preoperative CD or IBD-unclassified were excluded. De novo CD was diagnosed upon endoscopic evidence of five or more mucosal ulcers proximal to the ileal pouch any time after surgery and/or pouch fistula occurring more than three months after ileostomy closure. RESULTS: The study cohort consisted of 400 patients with a median follow-up of 44.0 (IQR 11-113) months. Sixty-two (16%) patients developed de novo CD 28.0 (IQR 6-67) months following ileostomy closure. Survival analysis of TNFi era patients revealed a significant increase in de novo CD risk in those with preoperative TNFi exposure. Multivariable proportional hazards modelling revealed two independent predictors for de novo CD development: older age was protective (HR 0.89 per 5-year increase; P = 0.009) and preoperative TNFi exposure was hazardous (HR 2.10; P = 0.011). CONCLUSION: This prospective study is the first to suggest an association between preoperative TNFi exposure and the development of de novo CD.