Funding for this research was provided by:
National Natural Science Foundation of China (No. 81973129)
Received: 5 September 2019
Accepted: 6 November 2019
First Online: 28 November 2019
Ethics approval and consent to participate
: Study protocols for NHANES were approved by the National Center for Health Statistics ethnics review board. All the participants signed the informed consent before participating in the study.
: Not applicable.
: The authors declare that they have no competing interests.