4AT Rapid Clinical Test For Delirium

Provides rapid initial screening of delirium and cognitive impairment based on patient alertness, abbreviated mental test, attention and changes in mental function.

Refer to the text below the calculator for more information on the 4AT and its usage.

The 4AT facilitates the rapid screening of delirium and cognitive impairment based on four easy to assess items:

  • Alertness;
  • AMT4 (Abbreviated Mental Test - 4)
  • Attention;
  • Acute change or fluctuating course.

Items 1-3 are rated on observation of the patient during the assessment whilst item 4 requires information from several sources.

4AT Score Interpretation
≥4 Possible delirium +/- cognitive impairment
1-3 Possible cognitive impairment
0 Delirium or severe cognitive impairment unlikely (but delirium still possible if “acute change or fluctuating course” information is incomplete)
1

Alertness

This includes patients who may be markedly drowsy (eg. difficult to rouse and/or obviously sleepy during assessment) or agitated/hyperactive. Observe the patient. If asleep, attempt to wake with speech or gentle touch on shoulder. Ask the patient to state their name and address to assist rating.
2

AMT4

Age, date of birth, place (name of the hospital or building), current year.
3

Attention

Ask the patient: “Please tell me the months of the year in backwards order, starting at December.” To assist initial understanding one prompt of “what is the month before December?” is permitted.
4

Acute change or fluctuating course

Evidence of significant change or fluctuation in: alertness, cognition, other mental function (eg. paranoia, hallucinations) arising over the last 2 weeks and still evident in last 24hrs.
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4AT Rapid Clinical Delirium Test Explained

The 4AT is a bedside tool for delirium assessment that is easy and quick to administer with no special training required – so ready to be used in routine clinical practice. The 4AT is recommended for clinical use in multiple international guidelines and pathways.

The 4AT facilitates rapid screening based on four easy to assess items:

  • Alertness;
  • AMT4 (Abbreviated Mental Test - 4)
  • Attention;
  • Acute change or fluctuating course.

Items 1-3 are rated on observation of the patient during the assessment whilst item 4 requires information from several sources about the patient, e.g., from the assessor, other clinical staff, carers, file notes etc.

The table below summarizes the possible assessment results:

4AT Score Interpretation
≥4 Possible delirium +/- cognitive impairment
1-3 Possible cognitive impairment
0 Delirium or severe cognitive impairment unlikely (but delirium still possible if “acute change or fluctuating course” information is incomplete)

Given the use of the assessment in geriatric population, the assessor will need to account of communication difficulties (hearing impairment, dysphasia, lack of common language) when carrying out the test and interpreting the score.

The 2014 validation study by Bellelli et al. assessed the clinical performance of the 4AT in 236 patients (aged ≥70 years) admitted consecutively to an acute geriatrics ward and a department of rehabilitation over a period of 4 months.

4AT was administered by geriatricians, within 24 hours of admission, whilst a subsequent standard delirium diagnosis (DSM-IV-TR criteria) was obtained within 30 min by a different geriatrician unaware of the 4AT result. The main outcome measure was the accuracy of the 4AT in diagnosing delirium.

The assessment was found to have a sensitivity of 89.7% and specificity 84.1% for delirium so can be considered a sensitive and specific method of screening for delirium in hospitalised older people.

One of the subsequent validation studies, by De et al. confirmed that the 4AT is a sensitive and specific screening tool for delirium in geriatric inpatients, including patients with probable dementia and showed a 91% sensitivity even in non-English speaking patients.

It is important to note that amongst available delirium tools the 4AT has the largest diagnostic test accuracy evidence base, where a meta-analysis of 17 validation studies (Tieges et al. 2020) showed a pooled sensitivity of 88% and specificity of 88%.

The official site of the 4AT with several resources available can be found here.

 

References

Original reference

Bellelli G, Morandi A, Davis DH, Mazzola P, Turco R, Gentile S, Ryan T, Cash H, Guerini F, Torpilliesi T, Del Santo F, Trabucchi M, Annoni G, MacLullich AM. Validation of the 4AT, a new instrument for rapid delirium screening: a study in 234 hospitalised older people. Age Ageing. 2014; 43(4):496-502.

Validation reference

De J, Wand APF, Smerdely PI, Hunt GE. Validating the 4A's test in screening for delirium in a culturally diverse geriatric inpatient population. Int J Geriatr Psychiatry. 2017; 32(12):1322-1329.

Other references

Tieges Z, Maclullich AMJ, Anand A, Brookes C, Cassarino M, O'connor M, Ryan D, Saller T, Arora RC, Chang Y, Agarwal K, Taffet G, Quinn T, Shenkin SD, Galvin R. Diagnostic accuracy of the 4AT for delirium detection in older adults: systematic review and meta-analysis. Age Ageing. 2020; 11:afaa224.

Shenkin SD, Russ TC, Ryan TM, MacLullich AM. Screening for dementia and other causes of cognitive impairment in general hospital in-patients. Age Ageing. 2014; 43(2):166-8.

Specialty: Geriatrics

System: Nervous

Objective: Screening

No. Of Items: 4

Year Of Study: 2014

Abbreviation: 4AT

Article By: Denise Nedea

Published On: May 28, 2021 · 12:00 AM

Last Checked: May 28, 2021

Next Review: May 28, 2026