Funding for this research was provided by:
Korean Ministry of Health and Welfare (0820010)
Article History
Received: 16 March 2018
Accepted: 26 June 2018
First Online: 3 July 2018
Compliance with ethical standards
:
: The authors declare no conflict 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.
: Informed consent was not required because of the retrospective nature of the study.