Funding for this research was provided by:
National Research Foundation of Korea (2015R1A1A1A05001342)
Chungnam National University (2018-0543-01)
Text and Data Mining valid from 2019-05-25
Received: 11 October 2018
Accepted: 9 May 2019
First Online: 25 May 2019
Compliance with ethical standards
: The study was approved by the institutional review board of the participating hospital (approval number: 4-2015-0610). The study was conducted in accordance with the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards.
: The authors declare that they have no conflicts of interest.