Li, Wenwei
Wang, Bin
Article History
Received: 24 February 2022
Accepted: 5 August 2022
First Online: 10 August 2022
Declarations
:
: The NHIS is designed and operated by the National Center for Health Statistics (NCHS). In adherence to the tenets of the Declaration of Helsinki, the NCHS protocols were approved by the National Center for Health Statistics research ethics review board and every participant provided written informed consent.
: Not applicable.
: The authors declare that they have no competing interests.