Funding for this research was provided by:
Beijing Municipal Natural Science Foundation (No.7164249)
Capital’s Funds for Health Improvement and Research (No.2016-4-1101)
Text and Data Mining valid from 2019-02-14
Received: 23 June 2018
Accepted: 30 January 2019
First Online: 14 February 2019
Ethics approval and consent to participate
: The study obtained ethical approval (2017-P2–095-01) from the Medical Ethics Committee of Beijing Friendship Hospital, Capital Medical University, Beijing, P.R China. Given that the study was retrospective without any interventions in treatment and all the data were collected and analyzed anonymously, the requirement for informed consent was waived. Permissions for obtaining related medical records were approved by hosipital.
: Not applicable.
: The authors declare that they have no competing interests.
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