Text and Data Mining valid from 2018-08-09
Received: 7 March 2018
Accepted: 1 August 2018
First Online: 9 August 2018
Ethics approval and consent to participate
: This study was approved by the institutional review board (IRB) of the Yonsei University Health System Clinical Trial Center. The IRB waived the requirement for informed consent because we retrospectively reviewed the medical records.
: Not applicable
: The authors declare that they have no competing interests.
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