Funding for this research was provided by:
The Graduate School Doctoral Student Aid Program, Keio University, Japan (博士26-73)
Received: 7 July 2018
Accepted: 19 June 2019
First Online: 17 July 2019
Ethics approval and consent to participate
: The study was approved by the National Hospital Organization, Tokyo Medical Center Ethics Committee (Approval number: R14–062.
: Not applicable.
: The authors declare that they have no competing interests.