Adenoma per polypectomy as a training metric in colonoscopy: a retrospective analysis of trainee progression compared to expert performance.

Purpose: This study introduced adenomas per polypectomy (APP) as a novel metric for evaluating the progression of lesion discrimination skills among colonoscopy trainees.

Methods: This retrospective study was conducted at the National Cancer Center, Korea between March 2020 and February 2023. Nine colorectal surgeons who completed a structured 1-year colonoscopy training program were included, and their performance was compared with that of 5 expert endoscopists. APP was defined as the number of histologically confirmed adenomas among the total number of polypectomies performed. The APPs were calculated serially to assess changes from the beginning to the end of the training.

Results: A total of 8,072 colonoscopies were performed by 9 trainees and 11,687 by 5 experts. The average APP of the 9 trainees was 67.0%, which was significantly different from the 73.9% APP of the experts (P < 0.001). The APP progression of trainees exhibited 3 phases: phase 1 (<200 cases) showed increasing polyp detection and APP; phase 2 (200-500 cases) displayed a sharp rise in the number of polypectomies but a decline in APP; and phase 3 (>500 cases) demonstrated a decrease in the number of polypectomies with a moderate rise in APP. However, even in phase 3, the trainees' APP remained significantly lower than that of the experts (69.9% vs. 73.9%, P = 0.027).

Conclusion: APP, a measure of visual adenoma discrimination ability, undergoes 3 stages of progression during colonoscopy training. This progression suggests that the APP may serve as an additional metric for assessing the effectiveness of colonoscopy training.