Trends in massive transfusion practice for trauma in Japan from 2011 to 2020: a nationwide inpatient database study.

"Declarations Ethics approval and consent to participateThis study was approved by the Institutional Review Board of the University of Tokyo [approval number: 3501-(5) (May 19, 2021)]. The requirement for informed consent was waived because all data were de-identified. Consent for publicationNot applicable. Competing interestsThe authors have no conflicts of interest to declare. Competing interests The authors have no conflicts of interest to declare."

"Funding This work was supported by grants from the Ministry of Health, Labour and Welfare, Japan (21AA2007 and 22AA2003), and the Ministry of Education, Culture, Sports, Science and Technology, Japan (20H03907). There was no involvement of the funder in study design, data collection, data analysis, manuscript preparation and publication decisions."