Fig. 2

Adjusted OR with 95% CI for hospital mortality by (a) month and (b) academic quartile. Adjustment for the potential confounders of age, sex, ISS, GCS score, SBP, trauma etiology (blunt or penetrating), and admission phase (2002–2005, 2006–2009, 2010–2013, and 2014–2018). a The reference set was the group of patients admitted to the ED during first month (in Japan, April) of the academic year. b The reference set was the group of patients admitted to the ED during the first quartile (in Japan, April–June) of the academic year. CI confidence interval, ED emergency department, GCS Glasgow coma scale, ISS injury severity score, OR odds ratio, SBP systolic blood pressure