Text and Data Mining valid from 2020-03-24
Received: 18 February 2020
Accepted: 16 March 2020
First Online: 24 March 2020
Ethics approval and consent to participate
: Informed consent was obtained in the form of opt-out on the web-site, and those who rejected were excluded. The protocol for this retrospective observational study was approved by the ethics committee of the University of Tsukuba Hospital (Registration No. R01–271). The study conforms to the provisions of the Declaration of Helsinki in 1964 (as revised in Brazil in 2013).
: Not applicable.
: The authors declare that they have no competing interests.