Funding for this research was provided by:
National Natural Science Foundation of China (81672201, 81871794)
Received: 22 June 2020
Accepted: 11 March 2021
First Online: 17 March 2021
: This study was reviewed and approved by the institutional review board following the declaration of Helsinki principles in Xuanwu Hospital Capital Medical University. The data collection process was entirely anonymous. The types of questions asked could not bring up any singular information that would make participants identifiable in the database and the results are presented in an aggregate manner. A written informed consent was obtained from all participants of this study.
: Not applicable.
: The authors declare that they have no competing interests.