Jia, Gaizhen
Yuan, Ping
Funding for this research was provided by:
Social Science Planning Project of Yantai in Shangdong Province (No.ytsk2013-070)
Article History
Received: 13 June 2019
Accepted: 13 April 2020
First Online: 24 May 2020
Ethics approval and consent to participate
: The study design was approved by the Ethical Committee of Binzhou Medical College (No. ytsk2013–070). All the older adults gave written informed consent before participating in the house-to-house survey.
: Not applicable.
: The authors declare that they have no competing interests.