Funding for this research was provided by:
Ministry of Health, Labour and Welfare (19AA2007, H30-Policy-Designated-004)
Ministry of Education, Culture, Sports, Science and Technology (17H04141)
Received: 28 April 2020
Accepted: 6 August 2020
First Online: 12 August 2020
Ethics approval and consent to participate
: This study was approved by the Institutional Review Board at The University of Tokyo (Number: 3501-(3)). Given the anonymous nature of the database, informed consent was waived for this study.
: Not applicable
: The authors declare that they have no competing interests.