Funding for this research was provided by:
Chinese Academy of Medical Sciences (CAMS) Initiative for Innovative Medicine (No. 2017-I2M-1-001 and 2016-I2M-1-002)
Text and Data Mining valid from 2019-05-10
Received: 28 February 2019
Accepted: 18 April 2019
First Online: 10 May 2019
Ethics approval and consent to participate
: The institutional review board of Peking Union Medical College Hospital approved the study. For this retrospective study formal informed consent is not required.
: Not applicable.
: The authors declare that they have no competing interests.
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