Text and Data Mining valid from 2020-05-05
Received: 27 December 2019
Accepted: 8 April 2020
First Online: 5 May 2020
Ethics approval and consent to participate
: The study has been approved by the Ethics Committee of Xiangya School of Public Health, Central South University (XYGW-2019-056). Written informed consent was obtained from all participants before administering any study procedures.
: Not applicable.
: The authors declare that they have no competing interests.