Zeng, Jianying
Jian, Weiyan http://orcid.org/0000-0003-4886-7263
Funding for this research was provided by:
National Natural Science Foundation of China (71774003)
Article History
Received: 7 January 2019
Accepted: 8 April 2019
First Online: 19 April 2019
Compliance with ethical standards
:
: The authors have no conflicts to declare.
: The manuscript does not contain clinical studies or patient data. The need for ethic approval was waived because data were extracted from open database.
: The datasets analyzed during the current study are available in China Health and Retirement Longitudinal Study (CHARLS), carried out by the National School of Development of Peking University. [ExternalRef removed].