Received: 16 August 2019
Accepted: 28 November 2019
First Online: 3 December 2019
Ethics approval and consent to participate
: The institutional review board of Chungbuk National University Hospital approved the study protocol (IRB no. 2018–12–010-001). The need for informed consent was waived due to the retrospective nature of the study and because the data were anonymized.
: Not applicable.
: The authors declare that they have no competing interests.