Gastroenterology

Gastroenterology

Volume 143, Issue 3, September 2012, Pages 599-607.e1
Gastroenterology

Original Research
Clinical—Alimentary Tract
Validation of a Simple Classification System for Endoscopic Diagnosis of Small Colorectal Polyps Using Narrow-Band Imaging

https://doi.org/10.1053/j.gastro.2012.05.006Get rights and content

Background & Aims

Almost all colorectal polyps ≤5 mm are benign, yet current practice requires costly pathologic analysis. We aimed to develop and evaluate the validity of a simple narrow-band imaging (NBI)-based classification system for differentiating hyperplastic from adenomatous polyps.

Methods

The study was conducted in 4 phases: (1) evaluation of accuracy and reliability of histologic prediction by NBI-experienced colonoscopists; (2) development of a classification based on color, vessels, and surface pattern criteria, using a modified Delphi method; (3) validation of the component criteria by people not experienced in endoscopy or NBI analysis (25 medical students, 19 gastroenterology fellows) using 118 high-definition colorectal polyp images of known histology; and (4) validation of the classification system by NBI-trained gastroenterology fellows, using still images. We performed a pilot evaluation during real-time colonoscopy.

Results

We developed a classification system for the endoscopic diagnosis of colorectal polyp histology and established its predictive validity. When all 3 criteria were used, the specificity ranged from 94.9% to 100% and the combined sensitivity ranged from 8.5% to 61.0%. The specificities of the individual criteria were lower although the sensitivities were higher. During real-time colonoscopy, endoscopists made diagnoses with high confidence for 75% of consecutive small colorectal polyps, with 89% accuracy, 98% sensitivity, and 95% negative predictive values.

Conclusions

We developed and established the validity of an NBI classification system that can be used to diagnose colorectal polyps. In preliminary real-time evaluation, the system allowed endoscopic diagnoses of colorectal polyp histology.

Section snippets

Study Design/Setting

We conducted a prospective observational study to develop and validate a simple classification for the endoscopic diagnosis of colorectal polyps using NBI. The study was conducted in 4 phases (Figure 1), as follows: phase 1, evaluation of interobserver agreement for NBI-experienced colonoscopists in predicting colorectal polyp histology; phase 2, development of a classification system for endoscopic prediction of adenomatous vs hyperplastic histology by NBI-experienced colonoscopists; phase 3,

Phase 1: Experienced Raters

The performance characteristics for the experienced colonoscopist raters are shown combined in Table 2 and individually in Table 3. High levels (>90%) of accuracy, sensitivity, specificity, and predictive value for predicting adenomatous from hyperplastic histology were seen (Table 2), reaching 98% or higher when ratings were made with high confidence. Overall, 80% (471 of 590) of predictions were made with high confidence, although the proportion of polyps predicted with high confidence

Discussion

We report the development and validation of a new, simple classification system using NBI for real-time endoscopic prediction of colorectal polyp histology. In this study, we extensively evaluated the diagnostic performance characteristics of the classification system in differentiating adenomas from hyperplastic polyps using NBI without optical magnification. We took multiple steps to develop a reliable and accurate system and then to comprehensively validate its components and overall

Acknowledgments

The authors thank Michael Krier, MD, Tohru Sato, MD, and Robert Rouse, MD, for their assistance with data collection.

David Hewett and Tonya Kaltenbach shared first authorship.

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    Conflicts of interest These authors disclose the following: David Hewett, Shinji Tanaka, and Yasushi Sano are consultants for Olympus Medical Systems Corporation, Japan; Tonya Kaltenbach, Roy Soetikno, and Douglas Rex are consultants for Olympus Medical Systems Corporation, and have received research funding from Olympus America, Inc, USA; Brian Saunders is a consultant for, and has received teaching and research funding from, Olympus KeyMed (Medical & Industrial Equipment) Ltd, UK; and Thierry Ponchon is a consultant for Olympus France S.A.S., and has received research funding from Olympus Europa Holding GmbH, Germany.

    Study participants were advised of potential investigator conflicts of interest.

    Funding This study was partially funded by Olympus Medical Systems Corporation (Japan). The sponsor had no role in the design of the study or in the collection, analysis, interpretation, or reporting of the data or in the decision to submit the manuscript for publication.

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    Copyright © 2012 AGA Institute. Published by Elsevier Inc. All rights reserved.