Funding for this research was provided by:
Ministry of Health, Labour and Welfare (H23-Tokubetsu-Shitei-002, H24-Kenki-Shitei-002, H25-Kenki-Shitei-002 (Fukko))
Received: 13 February 2020
Accepted: 22 June 2020
First Online: 1 July 2020
Ethics approval and consent to participate
: The study protocol was approved by the Institutional Review Board of the Tohoku University Graduate School of Medicine. Written informed consent obtained from all participants.
: Not applicable.
: The authors declare that they have no competing interests.