Funding for this research was provided by:
2018 Hainan Provincial Natural Science Foundation for Youth (818QN319)
Article History
Received: 25 January 2019
Accepted: 13 May 2019
First Online: 7 June 2019
Ethics approval and consent to participate
: This study was approved by the Hainan Medical University Clinic Institutional Review board, and the need for patient consent was waived due to the retrospective study design.
: Not applicable.
: The authors declare that they have no competing interests.
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