Colonic Diverticular Disease and Diarrhea-Predominant Irritable Bowel Syndrome: An Etiological Link?

Abstract

Purpose: Colonic diverticular disease is common, and many of them report unexplained lower GI symptoms. Some have attributed these symptoms to irritable bowel syndrome (IBS), but whether IBS and diverticular disease are causally linked is uncertain. We aimed to evaluate this association in a representative population-based case-control study. Methods: A population-based, cross-sectional survey was conducted by mailing a valid symptom questionnaire to eligible residents of Olmsted County, MN, aged 30–95 years. IBS was defined by Rome II. Colonic diverticular disease was ascertained through complete medical record abstraction of all responders. Subjects with at least one colon test (barium enema, colonoscopy, or CT colonography) were included. Results: Among 2298 subjects (55% response rate), there were 1784 respondents with colon tests (78%): 959 women (54%); mean (± SD) age 65 (± 12). Colonic diverticular disease was identified in 43.1% (95% CI 40.7–45.4). Older age (≥60 years) was a significant predictor for diverticular disease (OR 2.21, 95% CI 2.00–2.44), but no association with gender was detected. Overall, IBS was reported by 8.1% (95% CI 6.3–10.2) of men and 15.0% (95% CI 12.8–17.4) of women. After adjusting for age and gender, the presence of IBS was significantly associated with an increased odds for diverticular disease (OR 1.80, 95% CI 1.30–2.50,). Relative to the non-IBS subgroup, diarrhea (D)- IBS and alternating (A)-IBS had significantly increased odds for diverticular disease (OR 2.01, 95% CI 1.14–3.53 and OR 2.65, 95% CI 1.19–5.93, respectively); constipation (C)- IBS was not associated. After adjusting for age and gender, higher somatic symptom score, abdominal pain relieved by bowel movement, diarrhea, lower abdominal pain and bloating were also each significantly associated with diverticular disease, while smoking, alcohol, marital status, education, and body mass index were not associated. Conclusion: There is a significantly increased frequency of colonic diverticular disease in subjects with D- and A-IBS in a US community, but not C-IBS. The results suggest that D-IBS and colonic diverticular disease may be etiologically connected, perhaps via localized inflammatory change.