Funding for this research was provided by:
National Natural Science Foundation of China (81401307)
Medical science and technology research funding project in Guangdong province (A2015112, 2016A0103038)
Received: 7 February 2018
Accepted: 5 July 2018
First Online: 19 July 2018
Ethics approval and consent to participate
: The study protocol was approved by the Institutional Review Board of the first affiliated hospital of Sun Yat-Sen University. This was a retrospective study, with rational and scientific protocol. Written human subject consent was obtained before the study.
: Not applicable.
: The authors declare that they have no competing interests.
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