A Comparative Analysis of Clinical Symptoms and Modified Pouchitis Disease Activity Index Among Endoscopic Phenotypes of the J Pouch in Patients With Inflammatory Bowel Disease.

Background: The modified pouchitis disease activity index (mPDAI) based on clinical symptoms and endoscopic findings is used to diagnose pouchitis, but validated instruments to monitor pouchitis are still lacking. We recently established an endoscopic classification that described 7 endoscopic phenotypes with different outcomes. We assessed symptoms and compared mPDAIs among phenotypes in inflammatory bowel disease (IBD).

Methods: We retrospectively reviewed pouchoscopies and classified them into 7 main phenotypes: normal (n = 25), afferent limb (AL) involvement (n = 4), inlet involvement (n = 14), diffuse (n = 7), focal inflammation of the pouch body (n = 25), cuffitis (n = 18), and pouch-related fistulas (n = 10) with a single phenotype were included. Complete-case analysis was conducted.

Results: One hundred and three IBD patients were included. The median mPDAI was 0 (IQR 0-1.0) in patients with a normal pouch. Among inflammatory phenotypes, the highest median mPDAI was 4.0 (IQR 2.25-4.75) in cuffitis, followed by 3.0 (IQR 2.5-4.0) in diffuse inflammation, 2.5 (IQR 1.25-4.0) in inlet involvement, 2.5 (IQR 2.0-3.5) in AL involvement, 2.0 (IQR 1.0-3.0) in focal inflammation, and 1.0 (IQR 0.25-2.0) in the fistula phenotype. Perianal symptoms were frequently observed in pouch-related fistulas (8/10, 80%) and cuffitis (13/15, 87%). Among patients with cuffitis, all had incomplete emptying (6/6, 100%).

Conclusions: We correlated the mPDAI with the endoscopic phenotypes and described the limited utility of symptoms in distinguishing between inflammatory phenotypes. Further studies are warranted to understand which symptoms should be monitored for each phenotype and whether mPDAI can be minimized after pouch normalization.