Patchy colitis, and young age at diagnosis and at the time of surgery predict subsequent development of Crohn's disease after ileal pouch‐anal anastomosis surgery for ulcerative colitis

BACKGROUND AND AIM: A proportion of patients having total proctocolectomy and ileal pouch‐anal anastomosis (IPAA) for ulcerative colitis (UC) are later diagnosed with Crohn's disease (CD). The aim of this study was to identify preoperative and perioperative predictors for the subsequent development of CD in patients who had IPAA for presumed UC. METHODS: A retrospective case–control study of patients undergoing IPAA surgery for presumed UC was undertaken. Cases were patients who had a revised diagnosis of CD after surgery. Preoperative and perioperative variables were examined and analyzed. RESULTS: Fifteen cases were compared with 39 controls. Patients aged ≤25 years at initial UC diagnosis were more likely to develop CD compared to those aged >25 years (odds ratio, OR [95% confidence interval, CI]: 7.1 [1.6–31.3]; P = 0.01). Patients aged ≤30 years at the time of colectomy had an increased risk of subsequent development of CD compared to those aged >30 years (OR [95% CI]: 4.5 [1.3–16.0]; P = 0.02). Cases were more likely to have patchy colitis on their colectomy specimen (OR [95% CI]: 6.7 [1.1–41.8]; P = 0.04). There was no significant difference between groups regarding transmural inflammation, ileitis, or fissuring ulcers on colectomy specimens, or preoperative C‐reactive protein (CRP), albumin, family history, and smoking status. CONCLUSION: Predictors of the development of CD in the pouch include young age at diagnosis and at the time of surgery, and patchy colitis in the resected colon.