Funding for this research was provided by:
Ministry of Health of the People's Republic of China
Received: 2 August 2018
Accepted: 11 December 2018
First Online: 15 February 2019
Ethics approval and consent to participate
: Participation in both surveys was voluntary, and only those who wished to participate did so. This study was granted exempt status by the Brookdale Research Institute internal review board.
: Not applicable.
: RM, RN and OB declare that they have no competing interests.
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