Received: 18 September 2018
Accepted: 9 January 2019
First Online: 17 January 2019
Ethics approval and consent to participate
: The Seoul National University Hospital Institutional Review Board (IRB) approved the collection and use of the clinical information for research purposes before the investigation was started and waived the requirement for informed consent (IRB No. H-1701-032-821).
: Not applicable.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.