Text and Data Mining valid from 2020-02-07
Received: 31 July 2018
Accepted: 30 January 2020
First Online: 7 February 2020
Ethics approval and consent to participate
: The Institutional Review Board (IRB) at Peking Union Medical College Hospital (PUMCH) approved this study (#S-K422). Consent to participate was not obtained from each participant.
: Not applicable.
: The authors declare that they have no competing interests.