Retrospective Study
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World J Gastroenterol. Aug 21, 2014; 20(31): 10927-10937
Published online Aug 21, 2014. doi: 10.3748/wjg.v20.i31.10927
Risk factors associated with missed colorectal flat adenoma: A multicenter retrospective tandem colonoscopy study
Li Xiang, Qiang Zhan, Xin-Hua Zhao, Ya-Dong Wang, Sheng-Li An, Yang-Zhi Xu, Ai-Min Li, Wei Gong, Yang Bai, Fa-Chao Zhi, Si-De Liu
Li Xiang, Qiang Zhan, Xin-Hua Zhao, Ya-Dong Wang, Yang-Zhi Xu, Ai-Min Li, Wei Gong, Yang Bai, Fa-Chao Zhi, Si-De Liu, Guangdong Provincial Key Laboratory of Gastroenterology, Department of Gastroenterology, Nanfang Hospital, Southern Medical University, Guangzhou 510000, Guangdong Province, China
Li Xiang, Department of Gastroenterology, Longgang Central Hospital, Shenzhen 518116, Guangdong Province, China
Qiang Zhan, Department of Gastroenterology, Wuxi City People’s Hospital Affiliated to Nanjing Medical University, Wuxi 214194, Jiangsu Province, China
Xin-Hua Zhao, Department of Gastroenterology, Mianyang Central Hospital, Mianyang 621000, Sichuan Province, China
Sheng-Li An, Department of Biostatistics, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou 510000, Guangdong Province, China
Author contributions: Xiang L and Zhan Q contributed equally to this work; all the authors approved the final version.
Supported by Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme (2011)
Correspondence to: Si-De Liu, Professor, Guangdong Provincial Key Laboratory of Gastroenterology, Department of Gastroenterology, Nanfang Hospital, Southern Medical University, Dadaobei Rd 1838, Guangzhou 510000, Guangdong Province, China. liuside2011@163.com
Telephone: +86-20-61641537 Fax: +86-20-87280770
Received: December 27, 2013
Revised: March 19, 2014
Accepted: May 29, 2014
Published online: August 21, 2014
Processing time: 236 Days and 6.5 Hours
Abstract

AIM: To determine the miss rate for colorectal flat adenomas during colonoscopy and the risk factors.

METHODS: Flat adenomas are frequently missed during colonoscopy. However, the risk factors that influence their miss rates are unclear. This was a multicenter, retrospective study in which patients diagnosed with colorectal adenomas at a diagnostic colonoscopy and followed within 3 mo by a second therapeutic colonoscopy were pooled out from the established database. The “per-patient” and “per-adenoma” adenoma miss rates (AMR) for overall adenomas and flat adenomas, and patient-, adenoma-, and procedure-related risk factors potentially associated with the “per-adenoma” AMR for flat adenomas were determined.

RESULTS: Chromoscopy and high-definition colonoscopy were not taken under consideration in the study. Among 2093 patients with colorectal adenomas, 691 (33.0%) were diagnosed with flat adenomas, 514 with concomitant protruding adenomas and 177 without. The “per-patient” AMR for flat adenomas was 43.3% (299/691); the rates were 54.3% and 11.3%, respectively, for those with protruding adenomas and those without (OR = 9.320, 95%CI: 5.672-15.314, χ2 = 99.084, P < 0.001). The “per-adenoma” AMR for flat adenomas was 44.3% (406/916). In multivariate analysis, older age, presence of concomitant protruding adenomas, poor bowel preparation, smaller adenoma size, location at the right colon, insufficient experience of the colonoscopist, and withdrawal time < 6 min were associated with an increased “per-adenoma” AMR for flat adenomas. The AMR for flat adenomas was moderately correlated with that for overall adenomas (r = 0.516, P < 0.0001). The AMR for flat adenomas during colonoscopy was high.

CONCLUSION: Patient’s age, concomitant protruding adenomas, bowel preparation, size and location of adenomas, proficiency of the colonoscopist, and withdrawal time are factors affecting the “per-adenoma” AMR for flat adenomas.

Keywords: Flat adenoma; Colorectal cancer; Miss rate; Risk factor; Colonoscopy

Core tip: The miss rate for flat adenomas during colonoscopy is high. Patient’s age, concomitant protruding adenomas, bowel preparation, size and location of adenomas, proficiency of the colonoscopist, and withdrawal time are factors affecting the “per-adenoma” adenoma miss rate for flat adenomas.