Funding for this research was provided by:
Ministry of Health, Labour and Welfare (H28-013)
Text and Data Mining valid from 2020-03-24
Received: 24 October 2019
Accepted: 17 March 2020
First Online: 24 March 2020
Ethics approval and consent to participate
: The institutional review board of the University of Tsukuba approved this study. Completion and return of the questionnaire, in combination with the explanatory letter, was considered to indicate voluntary and informed consent to participate.
: Not applicable.
: The authors declare that they have no competing interests.