Sa1040 PREDICTIVE CALCULATION FOR THE SESSILE SERRATED ADENOMA DETECTION RATE

Abstract

Introduction: The potential inclusion of the sessile serrated adenoma detection rate (SSADR) in the key performance indicators of quality colonoscopy has been rapidly gaining understandable interest, given the associated pathway may contribute to 30% of colorectal cancers, particularly in the proximal colon. However, obtaining and calculating colonoscopy performance indicators is generally time‐consuming and laborious, as it involves manually reviewing and matching colonoscopy results with pathology results. It has been proposed that a formula based on polyp detection rate of the unit and the individual could perform as a proxy for adenoma detection rate (ADR) (Francis 2011), which was modified to account for high polyp detectors, but no such predictive proxy for SSADR exists. Although the SSADR is highly correlated with the ADR, the two rates are not directly predicative of one another. Aim: Our aim was to determine whether polyp detection rate (PDR) predicts SSADR. Methods: Colonoscopy records from July 2014 to September 2017 were retrospectively examined at two regional hospital endoscopy units in Australia. Patients with inflammatory bowel disease, polyposis syndromes, preoperative indications, failed examination due to inadequate bowel preparation, anastomosis, obstructing mass and failed intubation were excluded. In our previously proposed modification to the Francis calculation, the ADR target of 25% was replaced with the Proximal PDR (Prox‐PDR) and the adenoma to polyp detection rate quotient (APDRQ) then calculated from this (APDRQ = Prox‐PDR ÷ PDR). The group average weighted APDRQ was then calculated (0.6349) and the individual's PDR was multiplied by the weighted APDRQ. For the SSADR calculation, the SS‐APRDQ was determined by (PDR ÷ Prox‐PDR) + (group weighted average PDR ÷ group weight average Prox‐PDR), which was then multiplied by the individual PDR to determine the calculated SSADR. These calculations were then compared with the confirmed SSADR. Results: A total of 10 571 colonoscopies were included. The mean number of completed colonoscopies per endoscopist was 352. The average age of patients was 58 years and 45% were male. Including all endoscopists, the average PDR for all indications was 60.6% (SD, 14.1%), the average ADR was 39% (SD, 10.8%), and the average SSADR was 12.6% (SD, 7.4%). Table 1 presents the PDR, Prox‐PDR, actual SSADR, and calculated SSADR. The calculated SSADR had a strong positive calculation with the actual SSADR (r = 0.8646, P < 0.00001) and only differed from the actual SSADR by a mean of −0.003%. This correlation increased as the required minimum scope number was increased to at least 50 in the study period (n = 10 414, r = 0.8873, P < 0.00001). Conclusion: It is possible to accurately estimate SSADR for an individual endoscopist by using a proposed calculation incorporating the Prox‐PDR. In this study, this result is highly correlated to their actual SSADR. This may be invaluable in estimating SSADR before obtaining histology confirmation or for estimating SSADR for large centers.