Osamu Toyoshima, Toshihiro Nishizawa, Masahide Arita, Yosuke Kataoka, Kosuke Sakitani, Shuntaro Yoshida, Hiroharu Yamashita, Keisuke Hata, Department of Gastroenterology, Toyoshima Endoscopy Clinic, Tokyo 1570066, Japan
Hidenobu Watanabe, Department of Pathology, Pathology and Cytology Laboratory Japan, Tokyo 1660003, Japan
Hidekazu Suzuki, Medical Education Center, Keio University School of Medicine, Tokyo 1608582, Japan
Author contributions: All authors were involved in designing the study; Toyoshima O, Nishizawa T and Suzuki H prepared the manuscript; Watanabe H was involved with histological diagnoses; Toyoshima O contributed to statistical analyses.
Institutional review board statement: This retrospective study was approved by the Ethical Review Committee of Hattori Clinic on September 7, 2017.
Informed consent statement: Written informed consents were obtained from the participants.
Conflict-of-interest statement: During the last five years, Toyoshima O received personal fees from Otsuka Pharmaceutical Co., Ltd. and Takeda Pharmaceutical Co., Ltd. outside of the submitted work; Suzuki H received scholarship funds for the research from Astellas Pharma Inc., Astra-Zeneca K.K., Otsuka Pharmaceutical Co., Ltd., Takeda Pharmaceutical Co., Ltd., and Zeria Pharmaceutical Co., Ltd. and received service honoraria from Astellas Pharma, Inc., Astra-Zeneca K.K., Otsuka Pharmaceutical Co., Ltd., Takeda Pharmaceutical Co., Ltd., and Zeria Pharmaceutical Co., Ltd.
STROBE statement: The authors have read the STROBE Statement-checklist of items, and the manuscript was prepared and revised according to the STROBE Statement-checklist of items.
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: Osamu Toyoshima, MD, Director, Department of Gastroenterology, Toyoshima Endoscopy Clinic, 6-17-5 Seijo, Setagaya-ku, Tokyo 1570066, Japan. email@example.com
Telephone: +81-3-54299555 Fax: +81-3-54299511
Received: February 25, 2018
Peer-review started: February 25, 2018
First decision: March 9, 2018
Revised: March 13, 2018
Accepted: March 18, 2018
Article in press: March 18, 2018
Published online: April 7, 2018