Narrow band imaging optical diagnosis of small colorectal polyps in routine clinical practice: the Detect Inspect Characterise Resect and Discard 2 (DISCARD 2) study

Abstract

BackgroundAccurate 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.MethodsNBI-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.FindingsOf 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.InterpretationThis 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.Trial registration numberThe study was registered with clinicaltrials.gov (NCT01603927).

Magnifying Narrow Band Imaging (NBI) for the Diagnosis of Localized Colorectal Lesions Using the Japan NBI Expert Team (JNET) Classification

“…Hattori et al [9] reported that the risk of failure to detect diminutive and small colorectal invasive cancers using the "resect and discard" strategy might be avoided by using the NICE classification. In another multicenter study, Rees et al [10] provided evidence that an NBI-assisted optical diagnosis could not currently be recommended for the diagnosis of colorectal polyps in the absence of NBI expertise. These negative findings might be attributable to the inclusion of a wide range of pathologies (from LGD to SM-s [T1a]) within the NICE Type 2 classification.…”

“…The NBI International Colorectal Endoscopic (NICE) classification, published by the Colon Tumor NBI Interest Group (CTNIG), uses the colors, vessels, and surface patterns observed during endoscopy to classify the results of nonmagnifying evaluations [7,8] . However, colonoscopists often encounter difficulties with cases classified as NICE Type 2, as this category includes a variety of pathologies ranging from low-grade dysplasia (LGD) to shallow submucosal invasive cancer (SM-s) [9,10] ; the former is suitable for endoscopic mucosal resection (EMR), whereas the latter is indicated for endoscopic submucosal dissection (ESD) [11] .…”

Virtual chromoendoscopy for the real-time assessment of colorectal polyps in vivo: a systematic review and economic evaluation

“…Some research has shown that studies conducted in academic or specialist centres tend to find better diagnostic accuracy outcomes than those conducted in generalist settings or community practice. 148 It is not possible to determine from this review how accurate NBI is for the real-time diagnosis of diminutive polyps when used in different settings. We also did not formally investigate the impact of the classification system used for characterising polyps in the studies.…”

“…This could impact on whether or not VCE technologies meet the PIVI criteria. The DISCARD 2 study, 148 which is a large, multicentre prospective UK study, concluded that NBI cannot be recommended for use in routine clinical practice, as when it is used by non-experts in this setting it does not result in a high enough concordance rate with histopathology for determining surveillance intervals. This study was not included in our systematic review as it did not meet the inclusion criteria as a result of only 22% of the colonoscopies being conducted using HD equipment.…”

A Web-Based Education Program for Colorectal Lesion Diagnosis with Narrow Band Imaging Classification

“…However, a recent multicenter study [7] indicated that the NBI International Colorectal Endoscopic (NICE) classification is not recommended for use in routine practice and proposed further study validating efficacy of a training program in NBI interpretation. For NBI training, sufficient exposure to key features in NBI findings is required to perform optical diagnosis comfortably [3].…”