The ATS aims to ensure that patients presenting to emergency departments (EDs) are treated in the order of their clinical urgency and allocated to the most appropriate assessment and treatment area. The ATS also helps to describe the departmental case-mix.

Australasian Triage Scale Category Treatment Acuity (Maximum waiting time for medical assessment and treatment) Performance Indicator Threshold
ATS 1 Immediate 100%
ATS 2 10 minutes 80%
ATS 3 30 minutes 75%
ATS 4 60 minutes 70%
ATS 5 120 minutes 70%

Five categories

The ATS utilises five categories from Category 1 – an immediately life-threatening condition that requires immediate simultaneous assessment and treatment – to Category 5 - a chronic or minor condition which can be assessed and treated within two hours.

Triage assessment generally takes no more than two to five minutes and be carried out by appropriately trained and experienced staff members.

The ATS is only used to describe clinical urgency. Separate measures are required to describe severity, complexity, quality of care, workload and staffing.

ACEM's pioneering role

We developed the ATS by revising and updating the National Triage Scale (NTS) which had been developed in the early 1990s.

We formalised and standardised the triage process to provide ED staff with a tool that would provide patients with the level and quality of care they required in a way that made the most efficient use of departmental resources, against a background of increasing demand and long ED waits.

Since the launch of the ATS in Australia and New Zealand in 2000 we have been the driving force behind its implementation and revision. This has included developing policies and guidelines in relation to its use and leading efforts to further develop its use and effectiveness.

Several international triage scales were developed from or been based on the ATS, including the Manchester Triage Scale (MTS) in the UK and the Canadian Triage and Acuity Scale (CTAS) in Canada.

Tools to help you on the job

ACEM Policy on the Australasian Triage Scale

Guidelines on the Implementation of the Australasian Triage Scale in Emergency Departments

Australasian College for Emergency Medicine (ACEM) Literature Review on the Australasian Triage Scale (ATS)

Emergency Triage Education KIT (ETEK) 

Emergency Department Triage Revisited 

Australian Triage Process Review 

Find more information on Triage in our Quality Standards for Emergency Departments document.