Funding for this research was provided by:
Peking Union Medical College (3332018200, 3332016018)
Capital Health Research and Development of Special (201614035)
Text and Data Mining valid from 2019-11-09
Received: 2 September 2019
Accepted: 28 October 2019
First Online: 9 November 2019
Ethics approval and consent to participate
: The studies were approved by Fuwai Hospital ethics committees, in accordance with the Helsinki Declaration.
: Not applicable.
: The authors declare that they have no competing interests.