Funding for this research was provided by:
National Natural Science Foundation of China (71774178)
Science and Technology Planning Project of Guangdong Province (2017A020212006)
Guangzhou Science and Technology Program key projects (201607010368)
National Major Science and Technology Projects of China (2018ZX10715004)
Received: 12 December 2019
Accepted: 7 January 2020
First Online: 20 January 2020
Ethics approval and consent to participate
: This study was approved by the Ethics Committees of Sun Yat-sen University (Approval number: #003 in 2017 Committee of School of Public Health, Sun Yat-sen University). Written informed consent was obtained from the participants before the baseline assessment.
: Not applicable.
: The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.