Oral mesalamine and clinical remission are associated with a decrease in the extent of long-standing ulcerative colitis

OBJECTIVE: To compare colonoscopy alone with surveillance biopsy for the determination of anatomic extent in long-standing ulcerative colitis (UC). To assess the influences of mesalamine use and clinical disease activity on the change of histologic extent with time. MATERIALS AND METHODS: Disease extent (proctosigmoiditis, left-sided colitis, or pancolitis) measured by colonoscopy and surveillance biopsy was compared among 212 consecutive patients with long-standing UC. Among the 102 patients who had 2 consecutive colonoscopies with surveillance biopsies, the following influences on change in histologic extent were determined: disease activity, mesalamine use, age at disease onset, folic acid, corticosteroid and azathioprine/6-mercaptopurine use, and time between colonoscopies. RESULTS: Agreement between gross and microscopic findings was poor (κ = 0.39). Colonoscopy underestimated and overestimated extent in 25.9% and 8.5%, respectively. Microscopic distribution between consecutive colonoscopies remained the same in 60.8%. Where distribution changed, an increase was twice as common as a decrease in extent. There was no difference in age at onset, time between colonoscopies, or disease duration among those with an increase, decrease, or no change in extent. Clinical remission and oral mesalamine were independently associated with 10.7 and 5.8 times the odds of a decrease in disease extent, respectively. Folic acid, topical mesalamine, corticosteroids, and immunomodulators did not influence change in extent. CONCLUSIONS: UC extent is best determined by surveillance biopsy. Among patients with long-standing UC, histologic extent fluctuates with time. Disease remission and oral mesalamine were independently associated with decreases in disease extent.