Predictive validity comparison of two five-level triage acuity scales.

Introduction: Each of the two most commonly used five-level triage tools in North America, the Emergency Severity Index and the Canadian Triage and Acuity Scale have been used as a measure of emergency department resource utilization in addition to acuity. In both cases, it is believed that patients triaged as having a higher level of acuity require a greater number of emergency department resources. We compared the ability of each tool to predict the emergency department resources for each emergency department visit and associated hospital admission and in-hospital mortality rates.

Methods: This is an observational, cohort study of a population-based random sample of patients triaged at two emergency departments over a 4-month period. Correlational analyses were performed to examine the relationship between the triage assessment and: (i) resource utilization, (ii) hospital admission, and (iii) in-hospital mortality.

Results: From 486 patients, analyses revealed the greatest correlation was between Emergency Severity Index and diagnostic resources [-0.54 (95% confidence intervals: -0.58, -0.50)] and the poorest correlation was between Canadian Triage and Acuity Scale and mortality [-0.16 (95% confidence intervals: -0.20, -0.12)]. No statistically significant differences (P<0.005) were observed between each tool 's ability to predict any of the outcomes measured.

Conclusion: No statistically significant difference was observed in the ability of Emergency Severity Index v. 3 and Canadian Triage and Acuity Scale to predict emergency department resource utilization or immediate patient outcomes. This ability is, at best, only moderate indicating that other, more accurate tools than measures of triage acuity are required for this purpose.