Endoscopist Serrated Polyp Detection Rate (SDR) Highly Correlates with Adenoma Detection Rate (ADR)

Abstract

Introduction: Sessile serrated polyps are important precursors of colon cancer, but are more difficult to detect at colonoscopy. While serrated polyp detection rate (SDR) may be an important measure of colonoscopy quality, an accurate diagnosis of a serrated polyp is dependent upon pathologist expertise. It is unclear whether established quality metrics of withdrawal time (WT) and adenoma detection rate (ADR) sufficiently correlate with SDR. The primary aim is to determine the correlation of SDR with WT and ADR. The secondary aim is to determine the SDR in high ADR endoscopists. Methods: This is a retrospective cohort study of all providers at a single academic medical center performing ≥200 eligible screening colonoscopies over a 26-month period (4/2014-5/2016). An eligible screening colonoscopy was a colonoscopy in a patient age 50-75 without history of neoplastic polyps. SDR and ADR are the proportion of screening colonoscopies in which a serrated polyp (SDR) or adenoma (ADR) was biopsied or removed. WT is the time spent on colonoscope withdrawal in screening colonoscopies in which no biopsy/polypectomy occurred. Endoscopists were stratified into tertiles by ADR (High/Intermediate/Low ADR Endoscopists). All data was abstracted from our institutional data warehouse which integrates pathology, demographics, and endoscopy reports. Results: The 24 endoscopists who met inclusion criteria performed a total of 15,168 screening colonoscopies (median volume 486; range 200-1126). All endoscopists had a mean WT of ≥6 minutes (range 6-20 min). The mean institutional ADR was 39% (range 21-59%) and SDR was 8% (range 0.5-19%). There was a strong positive correlation between WT and both ADR (r=0.72, p < 0.0001) and SDR (r=0.71, p < 0.0001; Fig 1). There was a very strong positive correlation between ADR and SDR (r=0.86, p < 0.0001; Fig 2). The pooled SDR among High ADR endoscopists was 13%, which was significantly higher than Intermediate (SDR 7%, p < 0.01) and Low (SDR 4%, p < 0.001) ADR endoscopists.Figure 1Figure 2Conclusion: Screening colonoscopy SDR varies widely between endoscopists, identifying important variations in screening colonoscopy quality. However, there is a very strong correlation between endoscopist ADR and SDR. As SDR is more dependent on pathologist expertise than ADR, there appears to be no additional benefit in calculating endoscopist SDR to measure screening colonoscopy quality. Improvements in ADR may lead to simultaneous improvements in SDR, though this requires further study.