Geriatrics
4AT (Delirium Screen)
Rapid bedside test for delirium.
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Background
The 4AT is a brief bedside tool for rapid screening of delirium and cognitive impairment, designed for use without special training. It has four items: Alertness, the AMT4 (a four-item abbreviated mental test of age, date of birth, place and current year), Attention (listing the months of the year backwards) and evidence of Acute change or fluctuating course. Items are weighted so that abnormal alertness and acute change each score heavily. The total ranges from 0 to 12 and takes only a couple of minutes to complete.
Interpreting the result
A score of 0 makes delirium and cognitive impairment unlikely; a score of 1–3 suggests possible cognitive impairment (and merits further assessment); and a score of 4 or above suggests possible delirium, with or without cognitive impairment. A positive screen should trigger a delirium work-up to find the cause — for example infection, medication effects, urinary retention, constipation or pain. The 4AT identifies patients who need assessment; it does not on its own diagnose the cause. The acute-change and alertness items carry particular weight because they capture the hallmark features of delirium.
Advice
A score ≥4 suggests possible delirium and should prompt a delirium work-up (e.g. infection, drugs, retention, pain).
Worked example
An 84-year-old admitted with a fall is drowsy and intermittently agitated (abnormal alertness, +4) and the nursing staff report she has become acutely more confused over the past day (acute change, +4), giving a 4AT of at least 8. This is in the range suggesting possible delirium and should prompt a full delirium work-up.
Pearls / pitfalls
- A score of 4 or more suggests possible delirium and should always trigger a search for the underlying cause.
- Delirium fluctuates, so a single normal score does not exclude it; repeat if suspicion remains.
- The tool detects the presence of delirium or cognitive impairment but does not distinguish them or identify the cause.
- Items marked untestable still contribute to the score and often themselves indicate significant impairment.
Evidence & validation
Developed by MacLullich, Bellelli and colleagues and validated for rapid delirium detection (with the validation published in Age and Ageing in 2014); it is recommended in UK and international delirium guidance for screening in acute and older-adult care.
Frequently asked questions
What 4AT score suggests delirium?
A score of 4 or more suggests possible delirium, with or without cognitive impairment, and should prompt a delirium work-up. A score of 1–3 suggests possible cognitive impairment, and 0 makes both unlikely.
Does the 4AT diagnose the cause of delirium?
No. It flags that delirium may be present, but it does not identify the cause. A positive screen should be followed by assessment for triggers such as infection, drugs, retention, constipation or pain.
Can the 4AT distinguish delirium from dementia?
Not directly. It detects acute cognitive disturbance, and the acute-change and alertness items help point towards delirium, but a collateral history and the time course are needed to separate delirium from underlying dementia.
What does "untestable" mean for scoring?
If a patient cannot attempt an item, it is scored as untestable and contributes points. This is deliberate, because inability to engage often itself reflects significant impairment or reduced alertness.
Does a normal 4AT rule out delirium?
Not entirely. Because delirium fluctuates, a single normal score can miss it, so if clinical suspicion persists the screen should be repeated and the patient reviewed over time.
References
- Bellelli G, Morandi A, Davis DHJ, et al. 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.
- NICE CG103: Delirium: prevention, diagnosis and management. 2010 (updated).
About the creator
Bellelli G, MacLullich A et al.
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