Real-Time Characterization of Diminutive Colorectal Polyp Histology Using Narrow-Band Imaging: Implications for the Resect and Discard Strategy

Abstract

BACKGROUND & AIMS Narrow-band imaging (NBI) allows real-time histologic classification of colorectal polyps. We investigated whether endoscopists without prior training in NBI can achieve the following thresholds recommended by the American Society for Gastrointestinal Endoscopy: for diminutive colorectal polyps characterized with high confidence, a ≥90% negative predictive value for adenomas in the rectosigmoid and a ≥90% agreement in surveillance intervals. METHODS Twenty-six endoscopists from 2 tertiary care centers underwent standardized training in NBI interpretation. Endoscopists made real-time predictions of diminutive colorectal polyp histology and surveillance interval predictions based on NBI. Their performance was evaluated by comparing predicted with actual findings from histologic analysis. Multilevel logistic regression was used to assess predictors of performance. Cumulative summation analysis was used to characterize learning curves. RESULTS The endoscopists performed 1451 colonoscopies and made 3012 diminutive polyp predictions (74.3% high confidence) using NBI. They made 898 immediate post-procedure surveillance interval predictions. An additional 505 surveillance intervals were determined with histology input. The overall negative predictive value for high-confidence characterizations in the rectosigmoid was 94.7% (95% confidence interval: 92.6%–96.8%) and the surveillance interval agreement was 91.2% (95% confidence interval: 89.7%–92.7%). Overall, 97.0% of surveillance interval predictions would have brought patients back on time or early. High-confidence characterization was the strongest predictor of accuracy (odds ratio = 3.42; 95% confidence interval: 2.72–4.29; P < .001). Performance improved over time, however, according to cumulative summation analysis, only 7 participants (26.9%) identified adenomas with sufficient sensitivity such that further auditing is not required. CONCLUSIONS With standardized training, gastroenterologists without prior expertise in NBI were able to meet the negative predictive value and surveillance interval thresholds set forth by the American Society for Gastrointestinal Endoscopy. The majority of disagreement in surveillance interval brought patients back early. Performance improves with time, but most endoscopists will require ongoing auditing of performance.

Narrow-Band Imaging: Clinical Application in Gastrointestinal Endoscopy

“…In several studies, NBI was demonstrated to allow a reliable optical diagnosis of colonic lesions when used by appropriately trained endoscopists, and to improve diagnostic accuracy in lesion assessment [73, 75-77]. At present, there is a paradigm shift in the management of diminutive colorectal polyps (≤5 mm), advocating the use of optical biopsy with endoscopic technologies rather than histopathology for polyp characterization and subsequent assignment of surveillance intervals, without affecting its efficacy in reducing the future risk of colorectal cancer [78, 79].…”

Prevalence of sessile serrated adenoma/polyp in hyperplastic-appearing diminutive rectosigmoid polyps

“…Other studies have reported that academic and community endoscopist can meet the PIVI threshold of at least 90% NPV for adenomas in diminutive rectosigmoid lesions 5,[9][10][11][12][13][14] , including when SSPs were counted as adenomas [9][10][11]13 . We found that absolute prevalence of SSPs in diminutive rectosigmoid lesions that appear hyperplastic was 0.6% to 2.1% according to pathology interpretations by three expert pathologists.…”

“…Also anecdotally, we have observed interpretations of SSA/P in rectosigmoid serrated lesions. The precise prevalence of SSA/P in diminutive rectosigmoid M A N U S C R I P T , or did not specify findings in the rectosigmoid 13 or excluded SSPs 14 . None of the studies used additional expert assessment of pathology to determine how interobserver variability in SSP interpretation would affect the prevalence of SSP in distal diminutive polyps.…”

The “valley sign” in small and diminutive adenomas: prevalence, interobserver agreement, and validation as an adenoma marker

“…Endoscopic criteria 4 can also be used to reliably identify most precancerous colorectal lesions as belonging to the conventional adenoma versus serrated class 5 . Commonly used endoscopic criteria for differentiation of conventional adenomas from serrated class lesions use surface features such as the microvascular pattern and the shape of pits 4 .…”