Funding for this research was provided by:
Japan Society for the Promotion of Science (JP 20K18889)
Received: 20 July 2020
Accepted: 4 November 2020
First Online: 20 November 2020
Ethics approval and consent to participate
: Not applicableThis study did not require ethics committee approval because the Japan Council for Quality Health Care open data includes information that has already been anonymized. The Ethics Committee at Iwate Medical University School of Medicine, to which the first author belongs, stipulates that it is not necessary to seek ethics committee approval for analysis of data that have already been anonymized by the organization providing the data. Further, the data used did not involve human subjects. The Japan Council for Quality Health Care nationwide database center allowed us to use the data, provided that it is properly quoted in the article. Qualified researchers may request data access by emailing the corresponding author. In such an event, the researchers will consult with the Japan Council for Quality Health Care nationwide database center before providing data access to the concerned parties.
: Not applicable
: The authors declare that they have no competing interests.