Received: 8 August 2017
Accepted: 23 January 2018
First Online: 30 January 2018
Ethics approval and consent to participate
: All procedures performed in this study involving human participants were approved by the Ethics Committee of the First Affiliated Hospital of Sun Yat-sen University. Informed consent was taken from all patients involved in this study.
: Not applicable.
: The authors declare that they have no competing interests.
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