Optical diagnosis expanded to small polyps: post-hoc analysis of diagnostic performance in a prospective multicenter study.

Background: Optical diagnosis can replace histopathology of diminutive (1 - 5 mm) polyps if surveillance intervals based on optical diagnosis of polyps have ≥ 90 % agreement with intervals based on polyp histology and if the negative predictive value (NPV) for predicting neoplastic histology in the rectosigmoid is ≥ 90 %. This study aims to assess whether small (6 - 9 mm) polyps can be included in optical diagnosis strategies.
Method: This is a post-hoc analysis of a prospective multicenter study in which 27 endoscopists, all performing endoscopies for the Dutch screening program, were trained in optical diagnosis. For 1 year, endoscopists recorded the predicted histology for all lesions detected using narrow-band imaging during 3144 consecutive colonoscopies after a positive fecal immunochemical test, along with confidence levels. Surveillance interval agreement and NPV were calculated for high confidence predictions for polyps of 1 - 9 mm and compared with histopathology. Surveillance interval agreement was calculated using the European Society of Gastrointestinal Endoscopy surveillance guideline.
Results: Surveillance interval agreement was 95.4 % (confidence interval [CI] 94.2 % - 96.4 %), and NPV for predicting neoplastic histology in the rectosigmoid 90.0 % (CI 87.3 % - 92.2 %). The reduction in histology (45.9 % vs. 30.5 %) and the proportion of patients who could have received direct surveillance advice (15.6 % vs. 7.3 %) was higher when small polyps were included ( P  < 0.001). T1 cancer was found in seven small polyps (0.33 %), five of which would have been discarded without histopathology.
Conclusion: Including small polyps in the optical diagnosis strategy improves its efficacy while maintaining performance thresholds. However, there is a small risk of missing T1 cancers when small polyps are included in the optical diagnosis strategy.
Competing Interests: Evelien Dekker and Paul Fockens both received equipment on loan from Olympus and FujiFilm. Evelien Dekker has received an unrestricted research grant from Fujifilm and consulting fees for medical advice from Tillots, FujiFilm, and Olympus. Paul Fockens has received personal fees for consulting from Medtronic, Fujifilm, Cook, Ethicon Endosurgery, and Olympus. The other authors have no relevant disclosures to report.
(© Georg Thieme Verlag KG Stuttgart · New York.)