Funding for this research was provided by:
korea government (NRF-2018R1C1B6005202)
Received: 23 August 2018
Accepted: 5 March 2019
First Online: 27 March 2019
Ethics approval and consent to participate
: The study protocol was approved by Korea University Anam Hospital Institutional Review Board (ED16357). Because of the study’s retrospective design, the need for consent to participate was waived.
: Not applicable.
: The authors declare that they have no competing interests.
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