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Article History

Received: 23 April 2021

Accepted: 7 October 2021

First Online: 23 October 2021

Declarations

:

: Ethical approval was obtained from the Ethics Committee of Chiba University Faculty of Medicine (No. 2493) and the National Center for Geriatrics and Gerontology (No. 992). Questionnaires with encrypted codes and an explanation of the study purpose and procedure were mailed to participants, so we could not identify individual participants. Participants were informed that participation was voluntary and that returning the self-administered questionnaire by mail was taken as implied informed consent. Our study conforms to the appropriate reporting guidelines for observational studies (cross-sectional studies) in accordance with the STROBE (Strengthening the Reporting of OBservational studies in Epidemiology) guidelines. The study was conducted according to the recommendations of the Declaration of Helsinki.

: Not applicable.

: The authors have no conflict of interest with respect to this research study.