333 Identifying the Link Between Adenoma and Serrated Polyp Detection Rates and the Effect of Withdrawal Time on Both During Screening Colonoscopies

Abstract

INTRODUCTION: Adenoma detection rate (ADR) and its surrogate marker, mean withdrawal time (WT) of ≥ 6 min, is the current golden metric for colonoscopy quality. Serrated polyp detection rate (SPDR) is also an important marker for CRC. Longer WTs are linked with higher ADRs. We aim to assess if there is a correlation between SPDR and ADR, and if the same link exists between WTs and SPDR, as it exists for WT on ADR. METHODS: Screening colonoscopies between 2012 and 2017 were evaluated. Endoscopists with < 40 colonoscopies and procedures with polyps >6 mm, and/or WTs >30 min were excluded. Data was grouped into fellow (FG) and attending (AG) groups. The bivariate association of SPDR and ADR was calculated by correlation coefficients. Statistical analysis was performed using chi-squared tests, two-sample t-tests, and ANOVA t-testing. RESULTS: A total of 5951 procedures performed by 51 fellows and 13 attendings were assessed. The MWT was 15.4 min, SD 4.72, average total procedure time (TT) was 28.3 min, and average ADR was 40%. WT had a strong positive correlation with ADR and TT. The average SPDR was 0.1, SD 0.056. SPDR had a positive correlation with WT and ADR. There were significant differences between FG and AG in ADR, WT, TT and in regression models between the two for TT. There was no difference in the mean SPDR between groups. SPDR had a strong positive correlation with ADR and WT in the AG. There was no significant difference between bowel prep vs. SPDR between groups. CONCLUSION: Our study demonstrates a strong linear relationship between WT, ADR and TT. While FG have a higher ADR compared with AG at the cost of a longer WT, how much ADR changes as WT increases is not significant. AG and FG had similar SPDRs, however, only for AG were SPDR positively correlated with longer WTs and higher ADRs. We postulate that given the increased technical difficulty in detecting sessile polyps, AG are better equipped to improve SPDRs with increased WT. Bowel prep scores had no effect on SPDR, explained by exclusion criteria including only fully completed colonoscopies, and therefore subpar prep patients were likely pre-excluded. Our study highlights the importance of expertise and training in the identification of sessile polyps, the association between high ADR and SPDR, and the positive effect of WT on SPDR. Kahi et al., identified variability in SPDR ranging from 1% to 18%, compared with much less variability seen in ADRs. As a result, our findings are worthy of validation in larger multiple center studies.