Received: 20 November 2019
Accepted: 12 June 2020
First Online: 15 June 2020
Ethics approval and consent to participate
: This study was approved by Institutional Review Committees of Tokyo Medical University, Toho University and Showa University. Informed consent from each study participant was waived due to retrospective design of this study in accordance with the legislations of the Institutional Review Committees of participating institutions.
: Not applicable.
: The authors declare that they have no competing interests.