Received: 4 April 2019
Accepted: 16 July 2019
First Online: 29 July 2019
Ethics approval and consent to participate
: This study was approved by the Institutional Review Board (IRB) of the Korea University Medical Center, Guro Hospital (2018GR0191). The medical records used in this study had been obtained previously as part of routine medical procedures. As the data in this study were collected and analyzed retrospectively, the study did not infringe upon the rights or welfare of the patients and did not require consent.
: Not applicable.
: The authors declare that they have no competing interests.