Text and Data Mining valid from 2019-01-01
Received: 6 September 2018
Accepted: 19 December 2018
First Online: 1 January 2019
Compliance with ethical standards
: The authors have no conflicts of interest to disclose or any funding.
: The institutional review board of Asan medical center approved the registry (study no.: 2015-1253). All procedures performed in this study were in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
: Informed consent was obtained before data collection.