EM · Australasian Triage Scale
The Australasian Triage Scale — categories, validity, reliability and the under-triaged patient
Also known as Australasian Triage Scale · ATS · Emergency triage · Five-level triage scale · Triage nurse assessment · Under-triage and over-triage · Time-to-treatment threshold · Triage validity and reliability · Inter-rater agreement (weighted kappa) · Did not wait
The Australasian Triage Scale (ATS) — the five-level urgency scale used across Australian and New Zealand emergency departments, used under ACEM policy. The five categories with their maximal acceptable times to clinical treatment (ATS 1 immediately, 2 within 10 minutes, 3 within 30 minutes, 4 within 60 minutes, 5 within 120 minutes); construct and criterion validity (ATS category predicts mortality, admission, ICU and resource use — Doherty’s stepwise inpatient mortality); reliability and inter-rater agreement measured by weighted kappa (fair-to-moderate, ~0.3–0.6, never perfect, best at the extremes); the triage nurse’s role and scope of practice (brief assessment, category allocation, first-line measur…
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Red flags
- Triage allocates urgency, not diagnosis — the patient who 'looks well' but is genuinely time-critical (occult sepsis, atypical ACS, early SAH) is the one who is under-triaged and deteriorates in the waiting room
- A normal or near-normal vital-sign set does not exclude a time-critical illness — rely on Considine’s physiological discriminators to up-triage when any single parameter is deranged, and re-triage when the trend worsens
- The ATS threshold is the maximal acceptable time to treatment initiation, not a target to aim for — a patient who meets ATS 2 criteria must be seen within 10 minutes regardless of departmental load
- The waiting patient must be re-triaged — failure to re-triage is the proximate cause of the waiting-room collapse; any change, complaint of new pain, or new concern from patient or relative mandates reassessment
- Pain is under-assessed and under-treated at triage — document a pain score and initiate analgesia; untreated severe pain is itself a marker of high acuity
- The did-not-wait rate rises with access block and overcrowding and tracks with subsequent adverse events — a climbing did-not-wait rate is a system safety signal, not a patient problem
Meet the patient
A 58-year-old man walks into triage with 40 minutes of central crushing chest pain, diaphoresis and nausea. He is anxious, pale, BP 148/92, HR 104, pain 8 out of 10. The triage nurse allocates him a number and the clock starts. The number she allocates will decide whether he is in a resuscitation bay within minutes or in a waiting room chair.[1]
This is the single most consequential minute of his ED stay. Two questions govern the triage decision, and they govern every triage decision: how quickly must this patient be seen? (the category answers) and is there a deranged vital sign that overrides how well he looks? (the physiological discriminator answers). Hold those two questions and the whole scale slots into place.[1]
References13ShowHide
- [1]Gerdtz M, Bucknall T. Australian triage nurses' decision-making and scope of practice Aust J Adv Nurs, 2000.PMID 11878360
- [2]Gerdtz MF, Bucknall TK. Triage nurses' clinical decision making. An observational study of urgency assessment J Adv Nurs, 2001.PMID 11529955
- [3]Considine J, LeVasseur SA, Charles A Development of physiological discriminators for the Australasian Triage Scale Accid Emerg Nurs, 2002.PMID 12568450
- [4]Doherty SR, Hore CT, Curran SW. Inpatient mortality as related to triage category in three New South Wales regional base hospitals Emerg Med (Fremantle), 2003.PMID 14631700
- [5]Considine J, LeVasseur SA, Villanueva E The Australasian Triage Scale: examining emergency department nurses' performance using computer and paper scenarios Ann Emerg Med, 2004.PMID 15520712
- [6]Richardson DB. Increase in patient mortality at 10 days associated with emergency department overcrowding Med J Aust, 2006.PMID 16515430
- [7]Gerdtz MF, Bucknall TK Influence of task properties and subjectivity on consistency of triage: a simulation study J Adv Nurs, 2007.PMID 17445021
- [8]Cooke MW, Jinks S. Does the Manchester triage system detect the critically ill? J Accid Emerg Med, 1999.PMID 10353042
- [9]van der Wulp I, van Baar ME, Schrijvers AJ. Reliability and validity of the Manchester Triage System in a general emergency department patient population in the Netherlands: results of a simulation study Emerg Med J, 2008.PMID 18573959
- [10]van Veen M, Moll HA Reliability and validity of triage systems in paediatric emergency care Scand J Trauma Resusc Emerg Med, 2009.PMID 19712467
- [11]Gerdtz MF, Chu M, Collins M, et al. Factors influencing consistency of triage using the Australasian Triage Scale: implications for guideline development Emerg Med Australas, 2009.PMID 19682012
- [12]Forero R, Mohsin M, McCarthy S, et al. Prevalence of morphine use and time to initial analgesia in an Australian emergency department Emerg Med Australas, 2008.PMID 18377403
- [13]Blake DF, Dissanayake DB, Hay RM, et al. 'Did not waits': a regional Australian emergency department experience Emerg Med Australas, 2014.PMID 24708003