Association between colonic diverticulosis and prevalence of colorectal polyps

Diverticulosis and colorectal polyps increase in frequency as the population ages. Proposed common mechanisms for both include lack of dietary fiber, increased saturated fats, and slow colonic transit time. The association of diverticulosis and colorectal polyps has been previously reported with conflicting results. Despite sharing common epidemiologic predisposing factors, the association between diverticulosis and colon polyps remains unclear and needs better clarification.

The primary aim of our study is to evaluate if there is any association between diverticular disease and colorectal polyps.

This is a retrospective cohort study. All consecutive patients who underwent colonoscopy between January 2009 and December 2011 were included, except those with history of inflammatory bowel disease, polyposis syndrome, and poor bowel preparation. Univariate and multivariate logistic regression analysis was conducted to analyze the association between colon polyps and diverticulosis. Hyperplastic polyps were excluded from the statistical analysis, and only pre-cancerous adenomas were included.

A total of 2,223 patients met the inclusion criteria. The prevalence of colorectal polyps in patients with diverticulosis was significantly higher than those without diverticulosis (odds ratio (OR) 1.54; 95 % confidence interval (CI) 1.27-1.80, p = 0.001). This association was found significant for all locations of polyps and all histological subtypes. There was also a statistically significant association between age, presence of diverticulosis, and colorectal polyps (OR 1.03; 95 % CI 1.02-1.04). The incidence of colorectal polyps increases as age advances in patients with diverticulosis, with the highest association in patients >70 years of age (OR 3.55; 95 % CI 2.50-5.04). There was no significant association between indication for colonoscopy and presence of colorectal polyps in patients with diverticulosis (OR 0.98; 95 % CI 0.95-1.01). The incidence of diverticulitis was low (<1 %), and there was no association between diverticulitis and colon polyps.

There is a significant association between diverticulosis and synchronous pre-cancerous colorectal polyps (adenomas). Patients with diverticulosis have a higher risk of colorectal polyps as compared to those without. This observation needs further validation by a large prospective cohort study.