Funding for this research was provided by:
National Key Basic Research and Development Program (2012CB517904)
Received: 17 September 2018
Accepted: 30 April 2019
First Online: 24 June 2019
Ethics approval and consent to participate
: This protocol was approved by the university ethics committee (The Second Xiangya Hospital of Central South University Review Board, No. S101, 2011) and the study was carried out in accordance with the Declaration of Helsinki. All study participants gave verbal informed consent. They were fully informed about the purpose, procedures, measurements, benefits and risks of the survey. Subjects under 18 years of age also obtained verbal informed consent from at least one parent/guardian. Data is collected anonymously and without any personal identifiers.
: Not applicable
: The authors declare that they have no competing interests.
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