Development and validation of the SIMPLE endoscopic classification of diminutive and small colorectal polyps^[*]

Abstract

Background Prediction of histology of small polyps facilitates colonoscopic treatment. The aims of this study were: 1) to develop a simplified polyp classification, 2) to evaluate its performance in predicting polyp histology, and 3) to evaluate the reproducibility of the classification by trainees using multiplatform endoscopic systems.

Methods In phase 1, a new simplified endoscopic classification for polyps – Simplified Identification Method for Polyp Labeling during Endoscopy (SIMPLE) – was created, using the new I-SCAN OE system (Pentax, Tokyo, Japan), by eight international experts. In phase 2, the accuracy, level of confidence, and interobserver agreement to predict polyp histology before and after training, and univariable/multivariable analysis of the endoscopic features, were performed. In phase 3, the reproducibility of SIMPLE by trainees using different endoscopy platforms was evaluated.

Results Using the SIMPLE classification, the accuracy of experts in predicting polyps was 83 % (95 % confidence interval [CI] 77 % – 88 %) before and 94 % (95 %CI 89 % – 97 %) after training (P  = 0.002). The sensitivity, specificity, positive predictive value, and negative predictive value after training were 97 %, 88 %, 95 %, and 91 %. The interobserver agreement of polyp diagnosis improved from 0.46 (95 %CI 0.30 – 0.64) before to 0.66 (95 %CI 0.48 – 0.82) after training. The trainees demonstrated that the SIMPLE classification is applicable across endoscopy platforms, with similar post-training accuracies for narrow-band imaging NBI classification (0.69; 95 %CI 0.64 – 0.73) and SIMPLE (0.71; 95 %CI 0.67 – 0.75).

Conclusions Using the I-SCAN OE system, the new SIMPLE classification demonstrated a high degree of accuracy for adenoma diagnosis, meeting the ASGE PIVI recommendations. We demonstrated that SIMPLE may be used with either I-SCAN OE or NBI.

^* SIMPLE Classification Investigator Team: U. Shivaji and S. Smith, Division of Gastroenterology, University of Birmingham, UK; J. Ishtiaq, Division of Gastroenetrology, Royal stoke University Hospital, UK; S. Pelitari, Division of Gastroenterology, City Hospital NHS trust, Birmingham, UK; M. Kawidlak, Division of Gastroenterology, University Hospitals Coventry Warwickshire, UK; R. Khan, Liver Unit, University of Birmingham, UK; A. Karimmalik, Division of Gastroenterology, Good Hope Hospital, Birmingham, UK.

• References

• 1 Zauber AG, Winawer SJ, O’Brien MJ. et al. Colonoscopic polypectomy and long-term prevention of colorectal-cancer deaths. N Engl J Med 2012; 366: 687-696
• 2 Nishihara R, Wu K, Lochhead P. et al. Long-term colorectal cancer incidence and mortality after lower endoscopy. N Engl J Med 2013; 369: 1095-1105
• 3 Rex DK, Kahi C, O’Brien M. et al. The American Society for Gastrointestinal Endoscopy PIVI (Preservation and Incorporation of Valuable Endoscopic Innovations) on real-time endoscopic assessment of the histology of diminutive colorectal polyps. Gastrointest Endosc 2011; 73: 419-422
• 4 Wanders LK, East JE, Uitentuis SE. et al. Diagnostic performance of narrowed spectrum endoscopy, autofluorescence imaging, and confocal laser endomicroscopy for optical diagnosis of colonic polyps: a meta-analysis. Lancet Oncol 2013; 14: 1337-1347
• 5 Ladabaum U, Fioritto A, Mitani A. et al. Real-time optical biopsy of colon polyps with narrow band imaging in community practice does not yet meet key thresholds for clinical decisions. Gastroenterology 2013; 144: 81-91
• 6 Hewett DG, Kaltenbach T, Sano Y. et al. Validation of a simple classification system for endoscopic diagnosis of small colorectal polyps using narrow-band imaging. Gastroenterology 2012; 143: 599-607
• 7 Rees CJ, Rajasekhar PT, Wilson A. et al. 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 2017; 66: 887-895
• 8 Kaltenbach T, Rastogi A, Rouse RV et.al. Real-time optical diagnosis for diminutive colorectal polyps using narrow-band imaging: the VALID randomised clinical trial. Gut 2015; 10: 1569-1577
• 9 Ignjatovic A, Thomas-Gibson S, East JE. et al. Development and validation of a training module on the use of narrow-band imaging in differentiation of small adenomas from hyperplastic colorectal polyps. Gastrointest Endosc 2011; 73: 128-133
• 10 Raghavendra M, Hewett DG, Rex DK. Differentiating adenomas from hyperplastic colorectal polyps: narrow-band imaging can be learned in 20 minutes. Gastrointest Endosc 2010; 72: 572-576
• 11 Rastogi A, Rao DS, Gupta N. et al. Impact of a computer-based teaching module on characterization of diminutive colon polyps by using narrow-band imaging by non-experts in academic and community practice: a video-based study. Gastrointest Endosc 2014; 79: 390-398
• 12 Patel SG, Schoenfeld P, Kim HM. et al. Real-time characterization of diminutive colorectal polyp histology using narrow-band imaging: implications for the resect and discard strategy. Gastroenterology 2016; 150: 406-418
• 13 Kodashima S, Fujishiro M. Novel image-enhanced endoscopy with i-scan technology. World J Gastroenterol 2010; 16: 1043-1049
• 14 Neumann H, Fujishiro M, Wilcox CM. et al. Present and future perspectives of virtual chromoendoscopy with i-scan and optical enhancement technology. Dig Endosc 2014; 26 (Suppl. 01) 43-51
• 15 Quirke P, Risio M, Lambert R. et al. Quality assurance in pathology in colorectal cancer screening and diagnosis – European recommendations. Virchows Arch 2011; 458: 1-19
• 16 Kudo S, Tamura S, Nakajima T. et al. Diagnosis of colorectal tumerous lesions by magnifying endoscopy. Gastrointest Endosc 1996; 44: 8-14
• 17 The Paris endoscopic classification of superficial neoplastic lesions. Esophagus, stomach, and colon: November 30 to December 1, 2002. Gastrointest Endosc 2003; 58: S3-43
• 18 Basford PJ, Longcroft-Wheaton G, Higgins B. et al. High-definition endoscopy with i-Scan for evaluation of small colon polyps: the HiSCOPE study. Gastrointest Endosc 2014; 79: 111-118
• 19 Hazewinkel Y, López-Cerón M, East JE. et al. Endoscopic features of sessile serrated adenomas: validation by international experts using high-resolution white-light endoscopy and narrow-band imaging. Gastrointest Endosc 2013; 77: 916-924
• 20 IJspeert JE, Bastiaansen BA, van Leerdam ME. et al. Development and validation of the WASP classification system for optical diagnosis of adenoma, hyperplastic polyps and sessile serrated adenoma/polyps. Gut 2016; 65: 963-970
• 21 Bouwens MW, de Ridder R, Masclee AA. et al. Optical diagnosis of colorectal polyps using high-definition i-scan: an educational experience. World J Gastroenterol 2013; 19: 4334-4343
• 22 Grassano L, Pagana G, Daperno M. et al. Asymptotic distributions of kappa statistics and their differences with many raters, many rating categories and two conditions. Biom J 2017; DOI: 10.1002/bimj.201700016.
• 23 Fleiss JL, Nee JC, Landis JR. Large sample variance of kappa in the case of different sets of raters. Psychol Bull 1979; 86: 974
• 24 Landis JR, Koch GG. The measurement of observer agreement for categorical data. Biometrics 1977; 33: 159-174
• 25 Rotondi MA, Donner A. A confidence interval approach to sample size estimation for interobserver agreement studies with multiple raters and outcomes. J Clin Epidemiol 2012; 65: 778-784
• 26 Repici A, Ciscato C, Correale L. et al. Narrow-band imaging international colorectal endoscopic classification to predict polyp histology: REDEFINE study (with videos). Gastrointest Endosc 2016; 84: 479-486
• 27 Higashi R, Uraoka T, Kato J. et al. Diagnostic accuracy of narrow-band imaging and pit pattern analysis significantly improved for less-experienced endoscopists after an expanded training program. Gastrointest Endosc 2010; 72: 127-135
• 28 Lee CK, Lee SH, Hwangbo Y. Narrow-band imaging versus I-Scan for the real-time histological prediction of diminutive colonic polyps: a prospective comparative study by using the simple unified endoscopic classification. Gastrointest Endosc 2011; 74: 603-609