Funding for this research was provided by:
National Natural Science Foundation of China (71273174, 71673187)
Shanghai Key Discipline Construction Project in Public Health (15GWZK1002)
Received: 21 December 2017
Accepted: 1 May 2018
First Online: 15 May 2018
Ethics approval and consent to participate
: The proposal of the study was reviewed and approved by the Chinese National Nature Science Fund Committee. The study was also approved by the Ethics Committee of School of Public Health, Shanghai Jiao Tong University. We obtained written informed consent from all the participants following a clarification the objectives and the procedure of the study, as well as the potential risks and benefits of participation before enrolling the participants.
: The authors declare that they have no competing interests.
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