Funding for this research was provided by:
Liaoning Nature Science Foundation (2015020491)
National Nature Science Foundation of China (81000995)
Received: 10 January 2018
Accepted: 6 May 2018
First Online: 24 May 2018
Ethics approval and consent to participate
: This study was approved by the Institutional Review Board of China Medical University (No. 2015000226). Additional patient consent for this retrospective study was not required.
: The authors declare that they have no competing interests.
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