Received: 4 March 2021
Accepted: 26 July 2021
First Online: 9 August 2021
: We protected the identity of patients’ compiled data according to the requirements of the Japanese Ministry of Health, Labor, and Welfare, dedicated to privacy, information technology, and civil rights. The Research Ethics Committee of Chiba University School of Medicine approved the study’s protocol (approval number 2,584). Since 2009, all survivors provided written informed consent for a prospective cohort study (approval number 826). Deaths before 2008 were not required to provide written informed consent as per the guidelines for retrospective studies in Japan and the ethics committee of Chiba University Hospital permit it (Study 2). The study database was anonymized. All experiments were performed in accordance with the relevant guidelines and regulations.
: Not applicable.
: The authors declare that they have no competing interests.