Funding for this research was provided by:
Ministry of Health, Labour and Welfare (H29-Policy-Designated-009 and H29-ICT-General-004)
Ministry of Education, Culture, Sports, Science and Technology (17H04141 and 16K09254)
Received: 26 February 2020
Accepted: 22 July 2020
First Online: 31 July 2020
Ethics approval and consent to participate
: The study was approved by the Institutional Review Board of the University of Tokyo. Informed consent was waived because of the anonymous nature of the data.
: Not applicable.
: The authors have disclosed that they do not have any potential conflicts of interest.