Text and Data Mining valid from 2019-11-12
Received: 23 July 2019
Revised: 8 September 2019
Accepted: 12 September 2019
First Online: 12 November 2019
Compliance with ethical statements
: The authors have no conflicts of interest to disclose.
: This study is a retrospective and observational study and does not contain any studies with human participants or animals. With the approval of the institutional review board of the Korea University Medical Center, no informed consent was asked.