He, Wenbo
Cao, Liujiao
Liu, Rui
Wu, Yi
Zhang, Wei
Article History
Received: 22 March 2022
Accepted: 26 August 2022
First Online: 6 September 2022
Declarations
:
: Informed consent was obtained from all subjects and/or their legal guardians. NHIS is approved by the Research Ethics Review Board of the National Center for Health Statistics and the U.S. Office of Management and Budget. All NHIS respondents provided oral consent prior to participation. Respondents were not directly involved in planning the study as it was done as a part of a regular demographic health survey. All procedures were performed in accordance with relevant guideline. All methods were carried out in accordance with STROBE Statement and regulations.
: Not applicable.
: The authors declare that they have no competing interests.