Funding for this research was provided by:
high level introduction of talent research start-up fund (HLITRSF2017)
Received: 9 October 2018
Accepted: 3 January 2019
First Online: 25 January 2019
Ethics approval and consent to participate
: This study received ethical approval from the Institutional Review Board of the First Affiliated Hospital of Chongqing Medical University. The Ethics Committee study protocol number was 20184501 and the IRB granted a waiver of consent for this retrospective study.
: Not applicable.
: The authors declare that they have no competing interests.
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