Funding for this research was provided by:
National Natural Science Foundation of China (71774104, 71974117)
National Natural Science Foundation of China (71473152)
China Medical Board (16-257)
Cheeloo Youth Scholar Grant (IFYT1810, IFYT181031, IFYT18032)
NHC Key Lab of Health Economics and Policy Research (NHC-HEPR2019002, NHC-HEPR2019001)
Received: 28 December 2020
Accepted: 11 August 2021
First Online: 26 August 2021
: The Ethical Committee of Shandong University reviewed and approved the study protocol. All participants gave their informed written consent for participation prior to the face-to-face interview.
: Not applicable.
: All authors declare no conflict of interest.