Received: 5 June 2017
Accepted: 13 September 2017
First Online: 21 September 2017
Ethics approval and consent to participate
: The medical ethical committee of the Third Affiliated Hospital of Southern Medical University granted research ethics approval. The reference number is not applicable. We obtained informed consent from each patient before any testing was performed.
: Not applicable.
: The authors declare that they have no competing interests.
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