Funding for this research was provided by:
the Research and Development Plan of the 13th five-year plan of Ningxia autonomous region (2016BZ02)
Text and Data Mining valid from 2020-03-20
Received: 18 December 2018
Accepted: 12 March 2020
First Online: 20 March 2020
Ethics approval and consent to participate
: This study was approved by the Institutional Review Board of the General Hospital of Ningxia Medical University (No. 2017–200). All the participants provided written informed consent before completing the survey and health examination.
: Not applicable.
: The authors declare that they have no competing interests.