Modified pouchitis disease activity index: a simplified approach to the diagnosis of pouchitis

Pouchitis is the most common complication of ileal pouch-anal anastomosis for ulcerative colitis. Our previous study suggested that symptoms alone are not reliable for the diagnosis of pouchitis. The most commonly used diagnostic instrument is the 18-point pouchitis disease activity index consisting of three principal component scores: symptom, endoscopy, and histology. Despite its popularity, the pouchitis disease activity index has mainly been a research tool because of costs of endoscopy (especially with histology), complexity in calculation, and time delay in determining histology scores. It is not known whether pouch endoscopy without biopsy can reliably diagnose pouchitis in symptomatic patients. The aim of the present study was to determine whether omitting histologic evaluation from the pouchitis disease activity index significantly affects the sensitivity and specificity of diagnostic criteria for pouchitis.

Ulcerative colitis patients with an ileal pouch-anal anastomosis and symptoms suggestive of pouchitis were evaluated. Patients with chronic refractory pouchitis and Crohn's disease were excluded. Patients with pouchitis disease activity index scores of seven or more were diagnosed as having pouchitis. Different diagnostic criteria were compared on the basis of the pouchitis disease activity index component scores. Nonparametric receiver-operating-characteristic curves were used to measure proposed pouchitis scores' diagnostic accuracy compared with diagnosis from the pouchitis disease activity index. The receiver-operating-characteristic area under the curve measured how much these diagnostic strategies differed from each other.

Fifty-eight consecutive symptomatic patients were enrolled; 32 (55 percent) patients were diagnosed with pouchitis. With the use of the pouchitis disease activity index as a criterion standard, the use of only symptom and endoscopy scores (modified pouchitis disease activity index) produced an area under the curve of 0.995. Establishing a cut-point of five or more for diseased patients resulted in a sensitivity equal to 97 percent and specificity equal to 100 percent.

Diagnosis based on the modified pouchitis disease activity index offers similar sensitivity and specificity when compared with the pouchitis disease activity index for patients with acute or acute relapsing pouchitis. Omission of endoscopic biopsy and histology from the standard pouchitis disease activity index would simplify pouchitis diagnostic criteria, reduce the cost of diagnosis, and avoid delay associated with determining histology score, while providing equivalent sensitivity and specificity.