Funding for this research was provided by:
National Natural Science Foundation of China (71904004)
Beijing Municipal Natural Science Foundation (9204025)
Received: 27 November 2019
Accepted: 31 August 2020
First Online: 14 September 2020
Ethics approval and consent to participate
: Ethics approvals for this study were obtained from the institutional review boards of the National Health Commission Ethics Committee. All participants provided written informed consent for household-based survey. Patient confidentiality will be protected in the following ways: 1) data are de-identifiers before their use in research and 2) the use of data for these purposes is closely overseen by the National Health Commission. The National Health Commission granted administrative permissions, which were required to access and use the data described in our study.
: Not applicable.
: No conflicts of interest have been declared.