Funding for this research was provided by:
CAMS Fundamental research fund for Central public welfare research institute (2018PT32004)
Text and Data Mining valid from 2019-04-08
Received: 9 November 2018
Accepted: 29 March 2019
First Online: 8 April 2019
Compliance with ethical standards
: The authors declare that they have no competing interests.
: The institutional board of Peking Union Medical College Hospital (PUMCH) reviewed and approved the study, the address of the approving ethics committee is No. 1 Shuai Fu Yuan, Dong Cheng District, Beijing, China, 100,730.
: The datasets used and analyzed during the current study are available from the corresponding author on reasonable request.