Received: 17 September 2020
Accepted: 7 December 2020
First Online: 14 December 2020
Ethics approval and content to participate
: This study was approved by the institutional review board of Jichi Medical University (Permission Number: A20-071) and independent ethics committees of all participating institutions and was conducted in accordance with the Declaration of Helsinki. Because of the retrospective nature of this study, the requirement of written informed consent was waived. Instead, opt-out consent documents were shown on the website of Jichi Medical University for patients who did not wish to participate in the study. The following institutions in Japan participated in the present study; Jichi Medical University, Tochigi Medical Center Shimotsuga, and Haga Red Cross Hospital.
: Not applicable.
: Hironori Yamamoto received research fee from Shionogi & Co., Ltd., Osaka, Japan. Other authors declare that they have no competing interest.