Received: 25 August 2020
Accepted: 10 December 2020
First Online: 7 January 2021
Ethics approval and consent to participate
: The study was approved by our institutional review board (Iwate Prefectural Central Hospital), which waived the requirement for individual patient consent because only routine patient data were used for this retrospective analysis. All experiments were performed in accordance with relevant guidelines and regulations.
: Not applicable.
: The authors declare that they have no competing interests.