Funding for this research was provided by:
Ministry of Health and Welfare (HI16C1501)
Received: 18 July 2018
Accepted: 28 January 2019
First Online: 4 February 2019
Ethics approval and consent to participate
: Retrospective data collection and analysis were approved by the Institutional Review Board of Kyungpook National University Chilgok Hospital. The need for informed consent was waived due to the retrospective design of the study.
: Not applicable.
: The authors declare that they have no competing interests.
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