Funding for this research was provided by:
the General Insurance Association of Japan (Not applicable)
Text and Data Mining valid from 2019-08-16
Received: 21 June 2019
Accepted: 12 August 2019
First Online: 16 August 2019
Ethics approval and consent to participate
: All collaborating hospitals in this study obtained individual local institutional review board approval for the Conduct of Human Research before the study was started. The requirement for informed consent was waived because of the anonymity of the data being used.
: Not applicable.
: The authors declare that they have no competing interests.