Funding for this research was provided by:
National Natural Science Foundation of China (81872674, 71573275)
Received: 19 March 2019
Accepted: 28 May 2019
First Online: 4 June 2019
Ethics approval and consent to participate
: All participants gave written informed consent prior to participating in the study. Each participant was clearly informed that he could decline or withdraw from the survey at any time. The e-questionnaire and written consent document were separately kept under a specific account and in locked drawers at the research sites, which were inaccessible to anyone but research staff. The study protocol and consent were approved by the Ethics Review Committee of the First Affiliated Hospital of China Medical University (Ethical Review  No. 38).
: Not applicable.
: The authors declare that they have no competing interest.