Text and Data Mining valid from 2019-10-07
Received: 28 April 2019
Accepted: 26 September 2019
First Online: 7 October 2019
Ethics approval and consent to participate
: This study was approved by the ethics committee of Peking Union Medical College Hospital, Beijing, China (Approval No. ZS-1602). Written informed consent was obtained from the next of kin of each patient.
: Not applicable.
: The authors declare that they have no competing interests.