Received: 26 January 2021
Accepted: 10 May 2021
First Online: 21 June 2021
: The CLHLS was carried out in accordance with The Code of Ethics of the World Medical Association (Declaration of Helsinki) for experiments involving humans and was approved by the Research Ethics Board at Baycrest. The CLHLS study was approved by the Biomedical Ethics Committee of Peking University (IRB00001052–13074). All participants or their legal representatives signed written consent forms in the baseline and follow-up surveys.
: Not applicable.
: DG is a Senior Editorial Board Member of BMC Geriatrics. YY is an Editorial Board Member of BMC Geriatrics. CB, MG, JSJ, and YZ have no competing interest.