Study design, setting, and ethical approval

This is a prognostic study performed as a sub-analysis of a multicenter prospective descriptive cross-sectional study conducted by the Japanese Association for Acute Medicine (JAAM) Focused Outcomes Research in Emergency Care in Acute Respiratory Distress Syndrome, Sepsis and Trauma (FORECAST) study group¹⁵. The JAAM FORECAST TRAUMA study recruited participants from April 1, 2016, to January 31, 2018, from 39 emergency departments and intensive-care units (ICUs) in tertiary hospitals and was registered at the University Hospital Medical Information Network Clinical Trial Registry. (UMIN-CTR ID: UMIN000019588). This study was approved under the condition that written informed consent should be obtained from either the patient or their next of kin by the JAAM and the Ethics Committee of each hospital (JAAM, 2014-01; Hokkaido University Graduate School of Medicine, Head institute of the FORECAST group, 014-0307) and was performed in accordance with Declaration of Helsinki.