Impact of Bowel Cleansing on Polyp and Adenoma Detection Rate: Post-Hoc Analysis of a Randomized Clinical Trial

To assess the impact of bowel cleansing quality on polyp detection rate (PDR) and adenoma detection rate (ADR) and explore predictors of lesion detection rate in patients undergoing colonoscopy.

This is a post-hoc analysis of a multicenter randomized controlled trial (RCT) comparing 1L polyethylene glycol plus ascorbate (1L PEG+ASC) vs. 4L PEG as bowel preparation for colonoscopy.

PDR was significantly higher (35.6% vs. 18.5%, p = 0.013), and ADR was higher even if not significantly (25.6% vs. 16.7%, p = 0.153) in patients with Boston Bowel Preparation Scale (BBPS) ≥6 over BBPS <6. Comparing patients with BBPS = 9 over BBPS = 7-8, no significant differences were found in PDR (34.5% vs. 38.4%, p = 0.483) nor ADR (24.1% vs. 27.2%, p = 0.553). At multivariable regression analysis, older age (OR = 1.042, 95%CI = 1.021-1.063; p < 0.001), shorter intubation time (OR = 0.891, 95%CI = 0.816-0.972; p = 0.010), higher withdrawal time (OR = 1.171, 95%CI = 1.094-1.253; p < 0.001) and full consumption of the first dose (OR = 8.368, 95%CI = 1.025-68.331; p = 0.047) were independently associated with ADR.

This post-hoc analysis of a RCT showed that excellent cleansing (BBPS = 9) over high-quality cleansing (BBPS = 7-8) does not significantly improve PDR or ADR. Neither cleansing success nor preparation types were independently associated with ADR. Compliance with bowel preparation, timing of colonoscopy and withdrawal time are key elements for adequate ADR with potential implications for reducing interval colorectal cancer.