Funding for this research was provided by:
Natural Science Foundation of Zhejiang Province (LQ17H060003)
Text and Data Mining valid from 2019-03-28
Received: 1 September 2018
Accepted: 6 March 2019
First Online: 28 March 2019
Ethics approval and consent to participate
: This study was approved by the ethics committee of The Second Affiliated Hospital, Zhejiang University School of Medicine.
: No consent was needed because the database is publicly available and does not include unique patient identifiers.
: The authors declare that they have no competing interests.
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