Text and Data Mining valid from 2019-01-30
Received: 7 April 2018
Accepted: 20 January 2019
First Online: 30 January 2019
Compliance with ethical standards
: Drs. Sung Uk Bae, Chun-Seok Yang, Sohyun Kim, Dae Ro Lim, Woon Kyung Jeong, Dae Dong Kim, Jae Hwang Kim, Eung Jin Shin, Yoo Jin Lee, Ju Yup Lee, Nam Kyu Kim, Seong Kyu Baek have no conflicts of interest or financial ties to disclose.
: IRB approval for this study across the multiple centers performed in accordance with the principles of the Declaration of Helsinki. The formal informed consent was waived.
: The formal informed consent was waived.