Article History
Received: 14 September 2018
Accepted: 24 October 2018
First Online: 26 October 2018
Compliance with ethical standards
:
: The authors declare that they have no conflicts of interest.
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. For this type of study formal consent is not required.
: The Asan Medical Center Clinical Research Ethics Committee approved this study and waived the requirement for informed consent due to the retrospective nature of the study with collection of anonymous-subject data (IRB Number: 2018-0339).