Risk factors for clinical phenotypes of Crohn's disease of the ileal pouch.

BACKGROUND: Crohn's disease (CD) of the pouch can occur in patients with colectomy and ileal pouch-anal anastomosis (IPAA) originally performed for a preoperative diagnosis of ulcerative colitis. The clinical presentations of CD of the pouch are inflammatory, fibrostenotic, and fistulizing. Risk factors for clinical phenotypes of CD of the pouch have not been characterized.
METHODS: A total of 78 eligible patients with CD of the pouch together with 294 nonselected non-CD patients with IPAA seen in the Pouchitis Clinic were enrolled, including 28 with inflammatory CD, 18 with fibrostenotic CD, and 32 with fistulizing CD. The clinical phenotypes of CD were diagnosed based on a combined assessment of clinical, endoscopic, radiographic, and histologic features. Three separate analyses were performed, and for each analysis, the outcome of interest was having one of the phenotypes versus not having it. A stepwise selection multivariable logistic regression analysis was used.
RESULTS: In the multivariable analysis, the risk factor for inflammatory CD was higher afferent-limb endoscopy scores (hazard ratio [HR] 1.87 95% confidence interval [CI] 1.54-2.27); the risk factors for fibrostenotic CD were higher afferent-limb (95% CI 1.81-3.48, HR 2.51) and higher cuff (95% CI 1.01-1.84, HR 1.36) endoscopy scores; and for fistulizing CD the risk factors were younger age (95% CI 0.93-0.99, HR 0.96), female gender (95% CI 1.35-6.97, HR 3.07), a preoperative diagnosis of indeterminate colitis (95% CI 1.72-9.34, HR 4.00), and no use of nonsteroidal antiinflammatory drugs (95% CI 1.31-8.25, HR 3.28).
CONCLUSIONS: Each of the three phenotypes of CD of the pouch was associated with certain risk factors, suggesting that each of these diseases has a different etiology and disease process. The identification and management of some of the modifiable risk factors may reduce CD-related morbidity.