Text and Data Mining valid from 2018-11-20
Received: 3 September 2018
Accepted: 12 November 2018
First Online: 20 November 2018
Ethics approval and conesnt to participate
: The study was approved by the Institutional Review Board of Yonsei University Severance Hospital, Seoul, Korea (#2018–1951-001).
: Not applicable.
: The authors declare that they have no competing interests.
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