Funding for this research was provided by:
Ministry of Trade, Industry and Energy (10072064)
Text and Data Mining valid from 2019-11-20
Received: 3 April 2019
Revised: 18 September 2019
Accepted: 18 October 2019
First Online: 20 November 2019
Compliance with ethical standards
: The scientific guarantor of this publication is Sang Min Lee.
: The authors declare that they have no conflict of interest.
: The statistician of our institution (Seon Ok Kim) kindly provided statistical advice for this manuscript.
: Written informed consent was waived by the institutional review board.
: Institutional review board approval was obtained.
: • retrospective• diagnostic or prognostic study• multicenter study