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Article History

Received: 20 April 2018

Accepted: 31 July 2018

First Online: 16 August 2018

Ethics approval and consent to participate

: The study was approved by Seoul National University Hospital Institutional Review Board (IRB no. 1605–028-760). 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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