Rees, Colin J., Rajasekhar, Praveen T., Wilson, Ana, Close, Helen, Rutter, Matthew D., Saunders, Brian P., East, James E., Maier, Rebecca, Moorghen, Morgan, Muhammad, Usman, Hancock, Helen, Jayaprakash, Anthoor, MacDonald, Chris, Ramadas, Arvind, Dhar, Anjan and Mason, James (2017) Narrow band imaging optical diagnosis of small colorectal polyps in routine clinical practice : the Detect Inspect Characterise Resect and Discard 2 (DISCARD 2) study. Gut, 66 . pp. 887-895. doi:10.1136/gutjnl-2015-310584

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Abstract

Background Accurate optical characterisation and removal of small adenomas (<10 mm) at colonoscopy would allow hyperplastic polyps to be left in situ and surveillance intervals to be determined without the need for histopathology. Although accurate in specialist practice the performance of narrow band imaging (NBI), colonoscopy in routine clinical practice is poorly understood.

Methods NBI-assisted optical diagnosis was compared with reference standard histopathological findings in a prospective, blinded study, which recruited adults undergoing routine colonoscopy in six general hospitals in the UK. Participating colonoscopists (N=28) were trained using the NBI International Colorectal Endoscopic (NICE) classification (relating to colour, vessel structure and surface pattern). By comparing the optical and histological findings in patients with only small polyps, test sensitivity was determined at the patient level using two thresholds: presence of adenoma and need for surveillance. Accuracy of identifying adenomatous polyps <10 mm was compared at the polyp level using hierarchical models, allowing determinants of accuracy to be explored.

Findings Of 1688 patients recruited, 722 (42.8%) had polyps <10 mm with 567 (78.5%) having only polyps <10 mm. Test sensitivity (presence of adenoma, N=499 patients) by NBI optical diagnosis was 83.4% (95% CI 79.6% to 86.9%), significantly less than the 95% sensitivity (p<0.001) this study was powered to detect. Test sensitivity (need for surveillance) was 73.0% (95% CI 66.5% to 79.9%). Analysed at the polyp level, test sensitivity (presence of adenoma, N=1620 polyps) was 76.1% (95% CI 72.8% to 79.1%). In fully adjusted analyses, test sensitivity was 99.4% (95% CI 98.2% to 99.8%) if two or more NICE adenoma characteristics were identified. Neither colonoscopist expertise, confidence in diagnosis nor use of high definition colonoscopy independently improved test accuracy.

Interpretation This large multicentre study demonstrates that NBI optical diagnosis cannot currently be recommended for application in routine clinical practice. Further work is required to evaluate whether variation in test accuracy is related to polyp characteristics or colonoscopist training.

Item Type:	Journal Article
Subjects:	R Medicine > RC Internal medicine
Divisions:	Faculty of Medicine > Warwick Medical School
Library of Congress Subject Headings (LCSH):	Colon (Anatomy) -- Diseases -- Treatment , Rectum -- Diseases -- Treatment , Colonoscopy, Colon (Anatomy) -- Histopathology, Rectum -- Histopathology
Journal or Publication Title:	Gut
Publisher:	B M J Group
ISSN:	0017-5749
Official Date:	April 2017
Dates:	Date Event April 2017 Published 19 April 2016 Available 20 January 2016 Accepted 18 August 2015 Submitted
Date of first compliant deposit:	23 August 2016
Volume:	66
Page Range:	pp. 887-895
DOI:	10.1136/gutjnl-2015-310584
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Open Access
Funder:	National Institute for Health Research (Great Britain) (NIHR), British society of gastroenterology, Great Britain. National Health Service (NHS)
Grant number:	PB-PG-0407-13309 (NIHR)

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