Received: 9 January 2018
Accepted: 18 January 2018
First Online: 25 January 2018
Ethics approval and consent to participate
: This study was approved by the Institutional Review Board of our hospital, and waved to inform the consent by the Institutional Review Board of our hospital because of retrospective study nature.
: Not applicable
: No author has any potential conflict of interest with respect to the research, authorship or publication of this article.
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