Effects of age, sex and pathological type on the risk of multiple polyps: A Chinese teaching hospital study

The lack of risk profile data on changes in multiple polyps identified by a colonoscopy constrains the creation of evidence-based guidelines. Our study aimed to investigate the relationship between size, location and histology of multiple polyps and patients' characteristics in a large teaching hospital-based Chinese population.

We conducted a large, case-control, retrospective analysis on polyps obtained from 8308 patients who presented at the Digestive Endoscopy Center, Changhai Hospital (Shanghai, China) from January 2013 to August 2015. In total 10572 polyps were analyzed, with risk factors extrapolated through chart reviews of patients' electronic medical records.

Single polyps were identified in 6843 (82.4%) patients while multiple polyps were found in 1465 (17.6%). A multivariate analysis indicated that men were more likely than women to have multiple polyps (P < 0.001). Compared with the single polyps group, the numbers of patients with multiple polyps increased significantly with age (P < 0.001). Multiple small (6-9 mm) non-advanced adenomas were more likely to be found than were diminutive (<5 mm) non-advanced adenomas (P < 0.001). While most advanced and non-advanced adenomas were diagnosed in patients with single adenomas (55.9% and 65.6%, respectively), advanced adenomas were more likely than non-advanced adenomas to be in multiples (P < 0.001).

Our data indicate that particular features of colorectal polyps, such as their large size, advanced histology, together with patients' characteristics, including their sex and age, are risk factors associated with multiple polyps during diagnosis, screening and surveillance.