Text and Data Mining valid from 2019-03-12
Received: 2 January 2019
Accepted: 4 March 2019
First Online: 12 March 2019
Ethics approval and consent to participate
: This study was approved by the Ethics Committee of the Peking University First Hospital, and the requirement for informed consent was waived.
: Not applicable.
: The authors declare that they have no competing interests.
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