Background: Colonic diverticular disease exhibits mucosal outpouchings through the large intestine. Common complications of this disease are diverticular bleeding and diverticulitis. Some patients with colonic diverticular disease have abdominal symptoms resembling irritable bowel syndrome (IBS). IBS is a functional gastrointestinal disorder with abdominal discomfort, bloating or pain associated with disturbed defecation and unclear etiology. Some studies have shown a high prevalence of colonic diverticular disease in patients with IBS.
Objective: To determine the association, clinical characteristics and factors associated with colonic diverticular disease in IBS patients compared with a control group.
Material and Method: A cross-sectional prospective study was conducted at the Gastroenterology Unit, Department of Medicine, Rajavithi Hospital, Bangkok during December 2007 to January 2009. The study collected data regarding clinical
characteristics, demographics and colonoscopic findings of colonic diverticular disease comparing among IBS patients,
defined by Rome III criteria and control group patients. The study was approved by the institutional ethics committee of
Rajavithi Hospital. Demographic data of patients were collected. The presence of diverticula, their location and number from
colonoscopic findings were recorded.
Results: One hundred and fifty patients were enrolled and analyzed. The patients comprised 75 patients in the IBS group and 75 patients in the control group. The prevalence of colonic diverticular disease in the total population was 17.3% (26 of 150). The IBS group had a higher prevalence of colonic diverticular disease than the control group with statistical significance (18 of 75, 24.0% in the IBS group vs. 8 of 75 or 10.7% in the control group, p = 0.031). Body mass index (BMI) more than 25 kg/m2, age more than 60 years and being male were associated with colonic diverticular disease without significance (28.1% in BMI >25 kg/m2 vs. 14.3% inBMI <25 kg/m2, p = 0.071, 23.0% in age >60 years vs.13.5% in age <60 years, p = 0.132 and 20.3% males vs. 15.1% females, p = 0.406). Type of IBS (IBS-C vs. IBS-D) did not affect the prevalence of colonic diverticular disease (25.8% in IBS-C and 23.1% in IBS-D, p = 0.791). There were no difference in the location of colonic diverticular disease and number of diverticuli between the IBS group and control group (p = 0.149 and 0.095).
Conclusion: An increased frequency of colonic diverticular disease was observed in patients with IBS. Increasing age, high
BMI and being male were factors associated with colonic diverticular disease. These results suggest that IBS and colonic
diverticular disease may have a common pathogenesis.

Keywords: Irritable bowel syndrome, Colonic diverticular disease, IBS with constipation (IBS-C), IBS with diarrhea (IBS-D)