Funding for this research was provided by:
National Research Foundation of Korea (NRF-2014R1A1A2053682)
Article History
Received: 11 September 2017
Revised: 10 December 2017
Accepted: 27 December 2017
First Online: 6 April 2018
Compliance with ethical standards
:
: The scientific guarantor of this publication is Nariya Cho.
: The authors of this manuscript declare no relationships with any companies whose products or services may be related to the subject matter of the article.
: No complex statistical methods were necessary for this paper.
: Institutional review board approval was obtained.
: Written informed consent was waived by the institutional review board.
: • retrospective• observational• performed at one institution