Funding for this research was provided by:
National Natural Science Foundation of China (81670611)
Text and Data Mining valid from 2019-02-11
Received: 29 May 2018
Accepted: 30 January 2019
First Online: 11 February 2019
Compliance with ethical standards
: The authors declare that they have no competing interests.
: The study was approved by the Ethics Committee of Peking Union Medical College Hospital (Beijing, China).
: Consent for publication was obtained from all the authors.