772 THE RELATIONSHIP BETWEEN THE ENDOSCOPIC WITHDRAWAL TIME AND ADENOMA/POLYP DETECTION RATE IN INDIVIDUAL COLONIC SEGMENTS. A KASID MULTICENTER STUDY

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Withdrawal time is one of the most important indicators of high-quality colonoscopy. We thus evaluated the relationship between withdrawal time and adenoma/polyp detection rates in individual colonic segments to determine appropriate colonoscopic withdrawal times for the right, proximal, and left colon. This was a prospective observational study performed on 724 patients (Asymptomatic healthy 50-80 years) who underwent screening or surveillance (≥5 years) colonoscopy from October 2015 to February 2017 by 12 endoscopists in Ten university hospitals. We prospectively measured the withdrawal times from the right colon (Cecum to HF), the proximal colon (Cecum to SF), and the left colon (Descending to rectum); polyp removal times were subtracted from the withdrawal times. Also, we evaluated the polyp detection rate (PDR), serrated polyp detection rate (SDR), adenoma detection rate (ADR), and number of adenomas per colonoscopy (APC), in individual colonic segments. The mean colon insertion time was 6.1±4.7 min, and the mean colon withdrawal times were 3.1±1.9 min for the right colon, 5.3±2.6 min for the proximal colon, 3.8±2.0 min for the left colon, and 9.1 ± 3.7 min for the total colon. In the right colon, when the withdrawal time was ≥ 2 min, the ADR (33.2 vs. 13.7%, p<0.001), PDR (41.1 vs. 16.7%, p<0.001), SDR (13.9 vs. 3.6%, p<0.001), and APC (0.52±0.04 vs. 0.20±0.04, p<0.001) were significantly higher than when the withdrawal time was < 2 min. In the proximal colon, when the withdrawal time was ≥ 4 min, the ADR (47.4 vs. 18.5%, p<0.001), PDR (56.0 vs. 24.2%, p<0.001), SDR (19.0 vs. 7.7%, p<0.001), and APC (0.90±0.07 vs. 0.30±0.05, p<0.001) were significantly higher than when the withdrawal time was < 4 min. Also, in the left colon, the ADR, PDR, and APC were significantly higher when the withdrawal time was ≥ 3 min than when it was < 3 min. Multivariate analyses showed that the ADR was significantly associated with a withdrawal time of ≥ 2 min in the right colon (OR: 2.98, 95% CI: 1.72-5.15 p<0.001), ≥ 4 min in the proximal colon (OR: 4.48, 95% CI: 3.15-6.36, p<0.001), and ≥ 3 min in the left colon (OR: 2.92, 95% CI: 1.97-6.78, p<0.001). The frequencies of polyp and adenoma detection appeared to be significantly increased when the withdrawal time was ≥ 2 min in the right colon, ≥ 4 min in the proximal colon, and ≥ 3 min in the left colon.View Large Image Figure ViewerDownload Hi-res image Download (PPT)