Diverticulosis morphology is associated with risk of diverticulitis

The size, number and distribution of diverticula vary greatly in patients with diverticulosis. We aimed to study the association between the morphology of diverticulosis assessed on colonoscopy and the risk of diverticulitis. We performed a retrospective, case-control study of cases with a history of diverticulitis and controls with diverticulosis without diverticulitis matched on sex, age (within 5 years) and year of colonoscopy. Diverticulosis characteristics were obtained from endoscopy reports and were categorized according to severity, extent, number and size. We used conditional logistic regression on matched pairs to calculate the odds of diverticulitis among patients with diverticulosis according to differing morphologic characteristics. We identified 85 cases with computed tomography-documented diverticulitis and 85 matched controls with diverticulosis without a diagnosis of diverticulitis. In cases, 60% had left-sided only diverticulosis, 2% had right-sided only and 38% had both right and left-sided diverticulosis; whereas in controls, the distribution was 53%, 18% and 29%, respectively. Cases were more likely to have large diverticula [odds ratio (OR), 3.33; 95% confidence interval (CI), 1.30-8.56 for left colon only and 1.89, 95% CI, 0.78-4.57 for both right and left]. Similarly, when the severity of diverticulosis was compared between the groups, cases were more likely to have moderate or severe diverticulosis (OR, 3.44; 95% CI, 1.51-7.84 for moderate and OR, 8.87; 95% CI, 2.98-26.37 for severe). Diverticulitis cases were more likely to have large diverticula and severe diverticulosis when compared to controls suggesting that size and severity are novel risk factors for diverticulitis.