Text and Data Mining valid from 2020-04-26
Received: 13 February 2020
Accepted: 21 April 2020
First Online: 26 April 2020
Ethics approval and consent to participate
: All data were anonymized and the requirement for informed consent was waived due to the study design. This study was approved by the institutional review board of Hiroshima University (approval number: E-746) and Kyoto Prefectural University of Medicine (approval number: ERB-C-1162).
: Not applicable
: The authors declare that they have no competing interests.