Received: 2 February 2019
Accepted: 13 September 2019
First Online: 28 October 2019
Ethics approval and consent to participate
: Institutional Review Board of Chungbuk National University Hospital, Cheongju, Republic of Korea has approved this study (IRB No.2012–03-024). The requirement of informed consent was waived since it was a retrospective study and there was no possibility to cause harm to the enrolled subjects. Medical information center of Chungbuk National University Hospital granted permission to access the raw data of patients’ records. All data analyzed were anonymized.
: Not applicable.
: The authors declare that they have no competing interests.