Retrospective Cohort Study
Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jul 14, 2016; 22(26): 6049-6056
Published online Jul 14, 2016. doi: 10.3748/wjg.v22.i26.6049
Development and validation of a risk score for advanced colorectal adenoma recurrence after endoscopic resection
Antonio Facciorusso, Marianna Di Maso, Gaetano Serviddio, Gianluigi Vendemiale, Nicola Muscatiello
Antonio Facciorusso, Marianna Di Maso, Nicola Muscatiello, Gastroenterology Unit, University of Foggia, 71100 Foggia, Italy
Gaetano Serviddio, Gianluigi Vendemiale, Internal Medicine Unit, University of Foggia, 71100 Foggia, Italy
Author contributions: Facciorusso A designed the study, performed the statistical analysis and wrote the paper; Muscatiello N and Di Maso M performed the treatment procedures and collected the data; Vendemiale G and Serviddio G revised the paper.
Institutional review board statement: This study was approved by the Institutional Review Board of the University of Foggia for retrospective evaluation of de-identified patients.
Informed consent statement: Patients were not required to give informed consent to the study because the analysis used anonymous clinical data that were obtained after each patient agreed to treatment by written consent.
Conflict-of-interest statement: None of the authors have received fees for serving as a speaker or are consultant/advisory board member for any organizations. None of the authors have received research funding from any organizations. None of the authors are employees of any organizations. None of the authors own stocks and/or share in any organizations. None of the authors own patents.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Antonio Facciorusso, MD, Gastroenterology Unit, Department of Medical Sciences, University of Foggia, Viale L.Pinto, 1, 71100 Foggia, Italy. antonio.facciorusso@virgilio.it
Telephone: +39-881-732154 Fax: +39-881-732135
Received: February 28, 2016
Peer-review started: February 29, 2016
First decision: March 31, 2016
Revised: April 1, 2016
Accepted: April 20, 2016
Article in press: April 20, 2016
Published online: July 14, 2016
Abstract

AIM: To develop and validate a risk score for advanced colorectal adenoma (ACA) recurrence after endoscopic polypectomy.

METHODS: Out of 3360 patients who underwent colon polypectomy at University of Foggia between 2004 and 2008, data of 843 patients with 1155 ACAs was retrospectively reviewed. Surveillance intervals were scheduled by guidelines at 3 years and primary endpoint was considered 3-year ACA recurrence. Baseline clinical parameters and the main features of ACAs were entered into a Cox regression analysis and variables with P < 0.05 in the univariate analysis were then tested as candidate variables into a stepwise Cox regression model (conditional backward selection). The regression coefficients of the Cox regression model were multiplied by 2 and rounded in order to obtain easy to use point numbers facilitating the calculation of the score. To avoid overoptimistic results due to model fitting and evaluation in the same dataset, we performed an internal 10-fold cross-validation by means of bootstrap sampling.

RESULTS: Median lesion size was 16 mm (12-23) while median number of adenomas was 2.5 (1-3), whereof the number of ACAs was 1.5 (1-2). At 3 years after polypectomy, recurrence was observed in 229 ACAs (19.8%), of which 157 (13.5%) were metachronous neoplasms and 72 (6.2%) local recurrences. Multivariate analysis, after exclusion of the variable “type of resection” due to its collinearity with other predictive factors, confirmed lesion size, number of ACAs and grade of dysplasia as significantly associated to the primary outcome. The score was then built by multiplying the regression coefficients times 2 and the cut-off point 5 was selected by means of a Receiver Operating Characteristic curve analysis. In particular, 248 patients with 365 ACAs fell in the higher-risk group (score ≥ 5) where 3-year recurrence was detected in 174 ACAs (47.6%) whereas the remaining 595 patients with 690 ACAs were included in the low-risk group (score < 5) where 3-year recurrence rate was 7.9% (55/690 ACAs). Area under the curve of the model was 0.81 (0.72-0.86) with an overall classification error rate of 0.09. The model was finally validated by means of 10-fold cross validation.

CONCLUSION: Our study provides support for the use of a novel risk score as a clinical predictor of ACA recurrence after colon polypectomy.

Keywords: Advanced colorectal adenoma, Colonoscopy, Colorectal cancer, Polypectomy, Survival

Core tip: This is a retrospective study to develop and validate a novel risk score aimed at predicting advanced colorectal adenoma (ACA) recurrence after endoscopic polypectomy. The score based on lesion size, number of ACAs and grade of dysplasia, considering 5 as cut-off point, defined two different risk groups: high-risk group (score ≥ 5) with a 3-year recurrence rate of 47.6% and low-risk group (score < 5) with a 3-year recurrence rate of 7.9%. Further evidence, provided by large randomized controlled trials, is necessary in order to completely address this important issue.