Funding for this research was provided by:
National Natural Science Foundation of China (81602941, 81573257)
Natural Science Foundation of Fujian Province (2016J0101)
Received: 11 February 2018
Accepted: 2 May 2019
First Online: 24 May 2019
Ethics approval and consent to participate
: This study was approved by the ethical review committee of the School of Public Health, Xiamen University (reference number: SPH-XMU2015006). Generally, written informed consent was obtained from each respondent prior to completion of the questionnaire survey. Verbal description and explanation of this study was performed particularly to those who were illiterate and verbal agreement from them have been recorded. For those who cannot understand the intention and meaning of this study, neither in written description nor in oral explanation (i.e. who may had severe cognitive impairment), written informed consent was obtained from their immediate family instead.
: Not applicable.
: The authors declare that they have no competing interests.
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