Funding for this research was provided by:
Gansu Health Industry Research Program (GWSKY2017-40)
Text and Data Mining valid from 2019-11-26
Received: 21 April 2019
Accepted: 28 October 2019
First Online: 26 November 2019
Ethics approval and consent to participate
: Ethical approval and consent to participate (LDYYLL2018-142) was obtained from the ethical committees of First Hospital of Lanzhou University, Lanzhou, China.
: Not applicable.
: The authors declare that they have no competing interests.