Impact of the academic calendar cycle on survival outcome of injured patients: a retrospective cohort study at a community emergency department in Japan

Background Commencement of a new academic cycle is presumed to be associated with poor patient outcomes. However, supportive evidence is limited for trauma patients treated in under-resourced hospitals, especially those who require specialized interventions and with little physiological reserve. We examined whether a new academic cycle affects the survival outcomes of injured patients in a typical Japanese teaching hospital. Methods This historical cohort study was conducted at a Japanese community emergency department (ED). All injured patients brought to the ED from April 2002 to March 2018 were included in the analysis. The primary exposure was presentation to the ED during the first quartile of the academic cycle (April–June). The primary outcome measure was the hospital mortality rate. Results Of the 20,945 eligible patients, 5282 (25.2%) were admitted during the first quartile. In the univariable analysis, the hospital mortality rate was similar between patients admitted during the first quartile of the academic year and those admitted during the remaining quartiles (4.1% vs. 4.4%, respectively; odds ratio [OR], 0.931; 95% confidence interval [CI] 0.796–1.088). After adjusting for the potential confounding factors of the injury severity score, age, sex, Glasgow coma scale score, systolic blood pressure, trauma etiology (blunt or penetrating), and admission phase (2002–2005, 2006–2009, 2010–2013, and 2014–2018), no statistically significant association was present between first-quartile admission and trauma death (adjusted OR 0.980; 95% CI 0.748–1.284). Likewise, when patients were subgrouped according to age of > 55 years, injury severity score of > 15, Glasgow coma scale score of