Funding for this research was provided by:
Korea Health Technology R&D Project (HI13C2163)
Mid-Career Researcher Program (2016R1A2B4011115)
Article History
Received: 14 May 2018
Accepted: 6 June 2018
First Online: 12 June 2018
Compliance with ethical standards
:
: The authors declare that they have no conflict of interest.
: This study was approved by the Institutional Review Board of Severance Hospital (4-2013-0857). 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.
: Written informed consent given by participants was exempted, because the study design was retrospective, and information was anonymized and de-identified prior to analysis.