Funding for this research was provided by:
National Research Foundation of Korea (NRF-2016R1C1B1009972)
Received: 18 May 2018
Accepted: 12 October 2018
First Online: 27 October 2018
Ethics approval and consent to participate
: This study was approved by the Institutional Review Board of Seoul St. Mary’s Hospital (No. KC17ZESI0505). Informed consent was not obtained because anonymous and de-identified information was used for the analysis.
: Not applicable.
: All authors declare that they have no competing interests.
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