Received: 14 December 2020
Accepted: 13 April 2021
First Online: 22 April 2021
: The study was approved by the Tokushukai Group Ethics Committee where obtaining the informed consent from study subjects was waived for the current study, but the Committee indicated that the conduct of the study be announced through the internet.
: We declare that the authors have no competing interests as defined by BMC, or other interests that might be perceived to influence the results and/or discussion reported in this paper.