Received: 27 March 2021
Accepted: 17 July 2021
First Online: 24 July 2021
: The study protocol was approved by the institutional ethics committee of Oita University (approval no. 1613; approval date: May 20, 2019).
: Since all patient data were obtained in an anonymous manner, the requirement for individual informed consent was waived.
: All authors have stated that there are no competing interests in connection with this article.