Real-time optical biopsy of colon polyps with narrow band imaging in community practice does not yet meet key thresholds for clinical decisions

Abstract

Background & aims: Accurate optical analysis of colorectal polyps (optical biopsy) could prevent unnecessary polypectomies or allow a "resect and discard" strategy with surveillance intervals determined based on the results of the optical biopsy; this could be less expensive than histopathologic analysis of polyps. We prospectively evaluated real-time optical biopsy analysis of polyps with narrow band imaging (NBI) by community-based gastroenterologists.

Methods: We first analyzed a computerized module to train gastroenterologists (N = 13) in optical biopsy skills using photographs of polyps. Then we evaluated a practice-based learning program for these gastroenterologists (n = 12) that included real-time optical analysis of polyps in vivo, comparison of optical biopsy predictions to histopathologic analysis, and ongoing feedback on performance.

Results: Twelve of 13 subjects identified adenomas with >90% accuracy at the end of the computer study, and 3 of 12 subjects did so with accuracy ≥90% in the in vivo study. Learning curves showed considerable variation among batches of polyps. For diminutive rectosigmoid polyps assessed with high confidence at the end of the study, adenomas were identified with mean (95% confidence interval [CI]) accuracy, sensitivity, specificity, and negative predictive values of 81% (73%-89%), 85% (74%-96%), 78% (66%-92%), and 91% (86%-97%), respectively. The adjusted odds ratio for high confidence as a predictor of accuracy was 1.8 (95% CI, 1.3-2.5). The agreement between surveillance recommendations informed by high-confidence NBI analysis of diminutive polyps and results from histopathologic analysis of all polyps was 80% (95% CI, 77%-82%).

Conclusions: In an evaluation of real-time optical biopsy analysis of polyps with NBI, only 25% of gastroenterologists assessed polyps with ≥90% accuracy. The negative predictive value for identification of adenomas, but not the surveillance interval agreement, met the American Society for Gastrointestinal Endoscopy-recommended thresholds for optical biopsy. Better results in community practice must be achieved before NBI-based optical biopsy methods can be used routinely to evaluate polyps; ClinicalTrials.gov number, NCT01638091.

Figure 1

Ex vivo test scores before and after completion of a computerized learning module. Scores improved for 10 of the 11 subjects who submitted complete pretest and posttest results data, and 12 of 13 subjects who submitted posttest results scored >90% accuracy on the posttest. The top line represents 2 subjects who had a pretest score of 96% and a posttest score of 100%.

Figure 2

Learning curves as a function of performance on nonoverlapping batches of 20 consecutive polyps per endoscopist assessed with high confidence. There was considerable batch-to-batch variation, which was more pronounced for individual participants than for the group mean overall and for specificity compared with sensitivity. There was no clear pattern of early learning with later stabilization of performance at a higher level. (A) Accuracy, (B) sensitivity, and (C) specificity for diminutive polyps. (D) Accuracy, (E) sensitivity, and (F) specificity for diminutive and small polyps combined. Each participant is represented by a different color. The group average is superimposed in red.

Figure 3

Learning curves as a function of performance on nonoverlapping batches of 20 consecutive polyps per endoscopist assessed with high or low confidence. There was considerable batch-to-batch variation, which was more pronounced for individual participants than for the group mean overall and for specificity compared with sensitivity. There was no clear pattern of early learning with later stabilization of performance at a higher level. (A) Accuracy, (B) sensitivity, and (C) specificity for diminutive polyps. (D) Accuracy, (E) sensitivity, and (F) specificity for diminutive and small polyps combined. Each participant is represented by a different color. The group average is superimposed in red.