Objective The Japan Acuity and Triage Scale (JTAS) was developed based on Canadian Triage and Acuity Scale in 2012 and has been implemented in many Japanese EDs. We assessed the validity of JTAS by examining the association between JTAS triage levels and throughput and clinical outcomes in adult patients.

Methods We conducted a retrospective analysis of prospectively collected clinical data in the ED of a Japanese tertiary-care hospital. We included self-presenting patients who were ≥16 years of age and triaged between June 2013 and May 2014. We assessed the association between the triage level and overall admission and admission to the intensive care units (ICUs) with multivariable logistic regression analysis adjusted with patients’ age and the time of visit and ED length of stay using the Kruskal-Wallis rank-sum test. We examined the predictive ability of JTAS for determining overall and ICU admission using receiver operating characteristic curves.

Results We included a total of 27 120 adult patients in our study. The OR for overall admission was greater with a higher triage level compared with the lowest urgency levels. ED length of stay was significantly longer with a higher JTAS level (p<0.001). The OR for ICU admission was greater in JTAS 1 (117.93 (95% CI 69.07 to 201.38)) and JTAS 2 (9.43 (95% CI 13.74 to 29.30)) compared with the lowest urgency levels. The areas under the curve for the predictive ability of JTAS for overall and ICU admission were 0.726 and 0.792, respectively.

Conclusion Our study suggests an association of JTAS acuity with overall admission, ICU admission and ED length of stay, thereby demonstrating the predictive validity of JTAS.