Text and Data Mining valid from 2019-12-01
Received: 14 November 2019
Accepted: 18 December 2019
First Online: 30 December 2019
Ethics approval and consent to participate
: This study was approved by the Institutional Review Board of Saiseikai Utsunomiya Hospital (No.2018-16). The requirement for obtaining informed consent from patients was waived because the data sets were pseudonymous and this study was observational.
: Informed consent was waived because of the anonymous nature of the data.
: The authors declare that they have no competing interests.