Chen, Xinlin
Su, Dai
Chen, Xinlan
Chen, Yingchun
Article History
Received: 2 April 2021
Accepted: 22 June 2021
First Online: 15 July 2021
Declarations
:
: The CHARLS was approved by the Ethical Review Committee of Peking University, China. All the participants signed the informed consent at the time of participation. All methods were carried out in accordance with relevant guidelines and regulations.
: Not applicable.
: The authors have no competing interests to declare.