Funding for this research was provided by:
Ministry of Education (NRF-2017R1D1A1B03033892)
Received: 3 January 2019
Accepted: 28 February 2019
First Online: 12 March 2019
Ethics approval and consent to participate
: This retrospective patient study was approved by Institutional Review Board of the Seoul National University Bundang Hospital, and the requirement for written informed consent was waived. This study complies with the standards of the Declaration of Helsinki and current ethics guidelines.
: Not applicable.
: The authors declare that they have no competing interests.
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