Li, Xiang
Liu, Xun
Article History
Received: 13 December 2020
Accepted: 8 January 2021
First Online: 4 February 2021
Ethics approval and consent to participate
: This study was approved by the Institutional Review Board of the National Center for Health Statistics NHANES. All participants gave their written informed consent.
: Not applicable.
: The authors declare that they have no conflict of interest.