Han Ah Lee, Yoo Ra Lee, Young-Sun Lee, Young Kul Jung, Ji Hoon Kim, Hyung Joon Yim, Yoon Tae Jeen, Jong Eun Yeon, Kwan Soo Byun, Yeon Seok Seo, Department of Internal Medicine, Korea University College of Medicine, Seoul 02841, South Korea
Hyunggin An, Department of Biostatistics, Korea University Anam Hospital, Seoul 02841, South Korea
Author contributions: Seo YS carried out the concept and design, provided administrative, technical or material support; Lee HA and Seo YS are responsible for methodology development, wrote, reviewed and/or revised the manuscript; Lee HA, Lee YR, Lee YS, Kim JH, An H, Yim HJ, Jeen YT, Yeon JE, Byun KS, and Seo YS retrograde data acquisition, analysis and interpretation; An H and Seo YS are responsible for learning supervision.
Institutional review board statement: This study protocol followed the ethical guidelines of the 1975 Declaration of Helsinki, and the institutional review board of Korea University Anam Medical Center.
Informed consent statement: The requirement for informed consent was waived owing to the retrospective nature of the study.
Conflict-of-interest statement: Authors have nothing to disclose.
Data sharing statement: Technical appendix, statistical code, and dataset available from the corresponding author at email@example.com. Consent was not obtained but the presented data are anonymized and risk of identification is low.
: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (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/
Corresponding author: Yeon Seok Seo, MD, PhD, Professor, Department of Internal Medicine, Korea University College of Medicine, 73 Goryeodae-ro, Seongbuk-gu, Seoul 02841, South Korea. firstname.lastname@example.org
Received: January 27, 2021
Peer-review started: January 27, 2021
First decision: February 24, 2021
Revised: March 10, 2021
Accepted: July 13, 2021
Article in press: July 13, 2021
Published online: July 28, 2021