Received: 3 May 2020
Accepted: 11 June 2020
First Online: 17 June 2020
Ethics approval and consent to participate
: This study was approved by the institutional review board of Kobe University Graduate School of Medicine and by the institutional review boards of the participating hospitals. Informed consent from participants was waived, as this is a retrospective study. Instead, we published the information regarding this study and granted occasions of refusing to participate in this study.
: Not applicable.
: All authors declare that they have no conflict of interest.