Funding for this research was provided by:
National Natural Science Foundation of China (81773502, 81703285)
Beijing Nova Program (Z181100006218085)
Natural Science Foundation of Beijing Municipality (7174350)
Text and Data Mining valid from 2019-09-09
Received: 22 April 2019
Accepted: 28 August 2019
First Online: 9 September 2019
Ethics approval and consent to participate
: The use of CLHLS data was approved by the Biomedical Ethics Committee of Peking University.
: Not applicable.
: The authors have declared that no competing interests exist.