Funding for this research was provided by:
National Natural Science Foundation of China (71774104, 71473152, 71974117)
China Medical Board (16-257)
Cheeloo Youth Scholar Grant (IFYT1810)
Shandong University (2012DX006)
NHC Key Laboratory of Health Economics and Policy Research (NHC-HEPR2019014)
Received: 13 September 2020
Accepted: 16 December 2020
First Online: 7 January 2021
Ethics approval and consent to participate
: The study protocol was approved by The Ethical Committee of ShandongUniversity School of Public Health. All participants gave their informed written consent for participation prior to the face-to-face interview.
: Not applicable.
: The authors declare that they have no competing interests.