Annual Scientific Meeting
Introduction: Microscopic colitis (MC) is a common cause of chronic watery diarrhea. Cross-sectional studies have suggested that patients with MC have a lower incidence of colon polyps compared to those without MC. However, existing literature is limited by a lack of longitudinal follow-up and the use of average-risk patients, rather than those with chronic diarrhea as controls. We aimed to further explore the association between MC and colon adenomas.
Methods: This retrospective cohort study included patients that underwent colonoscopy at Mayo Clinic (Rochester, MN) or Columbia University Medical Center (New York, NY) between 7/1/2006 and 12/31/2016. Consecutive cases with MC were identified using pathology databases at each center. Controls had chronic diarrhea, underwent colonoscopy, and did not have MC on biopsy. Cases and controls were matched 1:2 by age (+/- 3 years), sex, and date of index colonoscopy (+/- 6 months). Data was collected on demographics, tobacco and alcohol use, personal and family history of colon neoplasia, and presence of adenomas at the index or follow-up colonoscopies.
Results: The study included 376 patients with MC and 752 non-MC patients with chronic diarrhea. The median (range) age of patients was 64 (21, 88) years and 72% were female. Duration of follow-up was not significantly different between the 2 groups (total person years: cases 577, controls 972; p=0.99) and 51 subjects had a new adenoma on follow-up. There were no significant differences in age, sex, alcohol use, family history of colon neoplasia, and personal history of inflammatory bowel disease between cases and controls. Patients with MC were more likely to be current tobacco users (10% vs. 6%, p=0.02) and less likely to have a history of prior colon neoplasia (9% vs. 17%, p< 0.001). Patients with MC were significantly less likely to have colon adenomas at the time of their index colonoscopy (5% vs. 12%; odds ratio 0.36; 95% CI 0.21, 0.60; p< 0.001) after adjusting for tobacco use and history of prior lesions. However, when followed over time, there was no significant association between MC and risk of colon adenomas (Figure 1, p=0.45) after adjusting for tobacco use, history of prior lesions, and presence of adenoma at index colonoscopy.
Discussion: Patients with MC are less likely to have colon adenomas at their index colonoscopy compared to those with chronic diarrhea without MC. However, when followed longitudinally, there appears to be no significant association between MC and risk of colon adenomas.