Received: 4 May 2016
Accepted: 29 January 2018
First Online: 7 February 2018
Ethics approval and consent to participate
: The study protocol was approved by institutional review board of Kyung Hee University Hospital at Gangdong (IRB No. 2016–03-008). Consent from the patients was waived by IRB, as the study was retrospective.
: Not applicable.
: The authors declare that they have no competing interests.
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