Funding for this research was provided by:
National Natural Science Foundation of China (81272809)
Text and Data Mining valid from 2018-11-12
Received: 1 March 2018
Accepted: 23 October 2018
First Online: 12 November 2018
Ethics approval and consent to participate
: Ethical approval for this study was obtained from the Institutional Review Board of the First Affiliated Hospital of Sun Yat-Sen University (FAHSYSU). For this type of study formal consent is not required.
: Not applicable.
: The authors declare that they have no competing interests.
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