External validation of blue light imaging (BLI) criteria for the optical characterization of colorectal polyps by endoscopy experts

Madhav Desai1,2, Kevin Kennedy3 Hiroyuki Aihara4, Jacques Van Dam5, Seth Gross 6, Gregory Haber6, Heiko Pohl7, Douglas Rex8, John Saltzman4, Amrita Sethi9, Irving Waxman10, Kenneth Wang11, Michael Wallace12, Alessandro Repici 13, Prateek Sharma1,2

J Gastroenterol Hepatol. 2021 Apr 30. doi: 10.1111/jgh.15529. Online ahead of print.

Background and aim: Recently, the BLI Adenoma Serrated International Classification (BASIC) system was developed by European experts to differentiate colorectal polyps. Our aim was to validate the BASIC classification system among the US-based endoscopy experts.

Methods: Participants utilized a web-based interactive learning system where the group was asked to characterize polyps using the BASIC criteria: polyp surface (presence of mucus, regular/irregular and [pseudo]depressed), pit appearance (featureless, round/non-round with/without dark spots; homogeneous/heterogeneous distribution with/without focal loss), and vessels (present/absent, lacy, peri-cryptal, irregular). The final testing consisted of reviewing BLI images/videos to determine whether the criteria accurately predicted the histology results. Confidence in adenoma identification (rated “1” to “5”) and agreement in polyp (adenoma vs non-adenoma) identification and characterization per BASIC criteria were derived. Strength of interobserver agreement with kappa (k) value was reported for adenoma identification.

Results: Ten endoscopy experts from the United States identified conventional adenoma (vs non-adenoma) with 94.4% accuracy, 95.0% sensitivity, 93.8% specificity, 93.8% positive predictive value, and 94.9% negative predictive value using BASIC criteria. Overall strength of interobserver agreement was high: kappa 0.89 (0.82-0.96). Agreement for the individual criteria was as follows: surface mucus (93.8%), regularity (65.6%), type of pit (40.6%), pit visibility (66.9%), pit distribution (57%), vessel visibility (73%), and being lacy (46%) and peri-cryptal (61%). The confidence in diagnosis was rated at high ≥4 in 67% of the cases.

Conclusions: A group of US-based endoscopy experts hsave validated a simple and easily reproducible BLI classification system to characterize colorectal polyps with >90% accuracy and a high level of interobserver agreement.

1 Department of Gastroenterology, Kansas City VA Medical Center
2 Division of Gastroenterology, Hepatology and Motility, University of Kansas School of Medicine
3 Department of Biostatistics, St. Luke’s Hospital, Kansas City, Missouri
4 Division of Gastroenterology, Hepatology and Endoscopy, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts
5 Division of Gastroenterology, Hepatology and Nutrition, Keck School of Medicine University of Southern California, Los Angeles, California
6 Division of Gastroenterology and Hepatology, Department of Medicine, NYU Langone Medical Center
7 Division of Digestive and Liver Diseases, Columbia University Medical Center, New York, New York
8 Section of Gastroenterology and Hepatology, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire
9 Department of Gastroenterology and Hepatology, Indiana University School of Medicine, Indianapolis, Indiana
10 Gastroenterology, Hepatology and Nutrition, University of Chicago Medicine, Chicago, Illinois
11 Department of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota
12 Department of Gastroenterology and Hepatology, Mayo Clinic, Jacksonville, Florida, USA
13 Digestive Endoscopy Unit, Division of Gastroenterology, Humanitas Clinical and Research Center, Milan, Italy