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Article History

Received: 2 March 2018

Revised: 1 June 2018

Accepted: 7 June 2018

First Online: 28 June 2018

Compliance with ethical standards

:

: The scientific guarantor of this publication is Ijin Joo.

: 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.

: Written informed consent was waived by the institutional review board.

: This retrospective study performed at one institution was approved by the Institutional Review Board of Seoul National University Hospital.

: • retrospective• case-control study• performed at one institution