P1609 - Water Exchange Colonoscopy Decreased Right Colon Serrated Polyp Miss Rate: A Multicenter Prospective Randomized Tandem Study

Award: Presidential Poster Award

Chi-Liang Cheng, MD¹, Jui-Hsiang Tang, MD², Yu-Hsi Hsieh, MD³, Yen-Lin Kuo, MD¹, Kuan-Chieh Fang, MD⁴, Chih-Wei Tseng, MD³, I-Chia Su, MD¹, Chun-Chao Chang, MD, PhD⁴, Ke-Yun Zou, ⁵, Yun-Shien Lee, PhD⁵, Felix W. Leung, MD, FACG^6
1Evergreen General Hospital, Taoyuan, Taoyuan, Taiwan; ²New Taipei Municipal Tucheng Hospital, New Taipei, New Taipei, Taiwan; ³Dalin Tzu Chi Hospital, Chiayi, Chiayi, Taiwan; ⁴Taipei Medical University School of Medicine, Taipei, Taipei, Taiwan; ⁵School of Health Technology, Ming Chuan University, Taoyuan, Taoyuan, Taiwan; ⁶Sepulveda ACC/VAGLAHS/UCLA, North Hills, CA

Introduction: The NordICC randomized controlled trial (RCT) showed completion of an invited screening colonoscopy reduced the risk of colorectal cancer (CRC) incidence and death by 31% and 50%, respectively [NEJM 2022;387:1547]. Non-RCT showed protection was less in the proximal/right colon (PRC) [AJG 2021;116:967; Ann Intern Med 2018;168;481] where postcolonoscopy CRC (PCCRC) (6 months apart from the prior examination) occurred. 85% of PCCRCs were due to missed polyps [Gastroenterology 2020;158:1287]. An independent predictor of PCCRC is the PRC location [Gut 2012;61:1576] with considerable variability of proximal serrated polyps (SPs) detection rate (SPDR) (CGH 2011;9:42). Water exchange (WE) method with gasless insertion to the cecum in clear water maximized cleanliness during insertion and in RCT, WE improved right colon cleanliness, adenoma detection rate and SPDR [Tech Coloproctol 2022;26:35]. We tested the hypothesis that WE decreased right colon adenoma and SP miss rates (rAMR and rSPMR).

Methods: Patients were randomized to WE or CO2 insufflation at 3 Taiwan sites. During the first withdrawal, polypectomies were performed to the hepatic flexure. The right colon was then reexamined by a second blinded endoscopist for missed polyps. Miss rate was the number of additional adenomas and SPs divided by the total number detected in both examinations, respectively. The primary outcome was the combined rAMR and rSPMR determined by tandem inspection of the right colon using WE or CO2 colonoscopy.

Results: 386 patients were randomized (WE, n=195; CO2, n=191) with similar baseline characteristics and detection rates (Table). Compared to CO2, WE significantly decreased the combined rAMR and rSPMR (22.2% vs. 32.2%, P=0.0007), rSPMR (22.5% vs. 37.1%, P=0.0018), and diminutive rAMR (23.2% vs. 33.3%, P=0.04). Multivariate logistic regression showed that ≥2 SPs in the right colon was an independent predictor of rSPMR (odds ratio [OR], 3.47; 95% confidence [CI], 1.89 to 6.38), along with higher right colon Boston Bowel Preparation Scale score (OR, 0.55; 95% CI, 0.32 to 0.94). The variability in proximal SPDR was similar between the WE and CO2 groups.

Discussion: Correct guess rate of < 67% confirmed adequate blinding of tandem endoscopist. The right colon inspection times were similar, confirming equivalent withdrawal technique. Compared to CO2, WE significantly decreased the rSPMR. Variability in proximal SPDR was similar between WE and CO2-insufflated colonoscopy.




Disclosures:


Chi-Liang Cheng, MD¹, Jui-Hsiang Tang, MD², Yu-Hsi Hsieh, MD³, Yen-Lin Kuo, MD¹, Kuan-Chieh Fang, MD⁴, Chih-Wei Tseng, MD³, I-Chia Su, MD¹, Chun-Chao Chang, MD, PhD⁴, Ke-Yun Zou, ⁵, Yun-Shien Lee, PhD⁵, Felix W. Leung, MD, FACG⁶. P1609 - Water Exchange Colonoscopy Decreased Right Colon Serrated Polyp Miss Rate: A Multicenter Prospective Randomized Tandem Study, ACG 2023 Annual Scientific Meeting Abstracts. Vancouver, BC, Canada: American College of Gastroenterology.