Funding for this research was provided by:
Ministry of Education (NRF-2017R1A2A2A05001217, NRF-2017R1C1B2007258)
Received: 22 March 2019
Revised: 13 June 2019
Accepted: 8 July 2019
First Online: 26 July 2019
Compliance with ethical standards
: The scientific guarantor of this publication is Jeong Hoon Kim.
: 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.
: One of the authors has significant statistical expertise (Seo Young Park, 8 years of experience).
: Written informed consent was not required because of the nature of our study, which was a study based on research articles.
: Institutional Review Board approval was not required because of the nature of our study, which was a study based on research articles.
: • retrospective• cross-sectional study• performed at one institution