Patients With Ulcerative Colitis Do not Have a Decreased Risk of Diverticulosis

Abstract

Introduction: Diverticulosis is common in patients after age 60, with a prevalence of up to 40%. Studies outside the United States (U.S.) have described a lower prevalence of diverticular disease in patients with inflammatory bowel disease (IBD) than in non-IBD patients. The aim of this study was to assess the prevalence and risk factors for diverticulosis in ulcerative colitis (UC) in a U.S. tertiary center. Methods: We performed a retrospective review in patients over 50 years of age who underwent screening or surveillance colonoscopy from January 2006 to December 2013. Pathology was reviewed for all patients to eliminate cases of segmental colitis associated with diverticula (SCAD). We first assessed the prevalence of diverticulosis in UC patients compared to patients without IBD. Then we performed a nested case-control study comparing UC patients with diverticulosis (cases) to UC patients without diverticulosis (controls) to identify clinical predictors (disease extent or disease duration) of diverticulosis. Cases were matched 1:1 fashion based on age and gender. Cases were excluded if there was lack of data or a matched control. Statistical analysis included a Student’s t-test, chi-squared test, relative risk (RR) and adjusted RR using logistic regression. Results: We identified 573 UC patients and 16,695 patients without IBD who underwent colonoscopy. Of the patients, 25.1% of UC patients had diverticulosis, and 46.7% of non-IBD patients had diverticulosis, p<0.01. UC patients were younger (61.1 years vs. 62.8 years; p<0.01) and less likely to be female (46.3% vs. 59.4%; p<0.01). On univariate analysis the RR of diverticulosis= 0.56 (95% confidence interval [CI]: 0.49-0.64). On multivariate analysis adjusting for age and gender, RR of diverticulosis=1.03 (95% CI: 1.02-1.03). In the nested case-control study, 118 patients with UC with diverticulosis (cases) were matched to 118 patients with UC without diverticulosis (controls). The mean age of cases was 65.1 years (SD 8.9 years), and 42.3% were female, this was similar in the control group. The majority of diverticula were limited to the sigmoid/descending colon (68.6%). There were no differences between cases and controls in disease duration (16.7 years vs. 18.7 years; p=0.27) or extent of disease (pancolitis 50% vs. 60.1%; p=0.24). Conclusion: In this U.S.-based study, UC patients had similar rates of diverticulosis as non-IBD patients undergoing screening or surveillance colonoscopy. There were no identified predictors for the development of diverticulosis in patients with UC. These results are different than previously reported data in IBD patients in other countries and may represent unique dietary factors that contribute to the development of diverticulosis.