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4AT (Rapid Assessment Test for Delirium)
4AT: A rapid bedside assessment for delirium. Crucially, score patients who are "untestable" due to drowsiness or severe agitation, as this often indicates delirium.
Select the best option for each item
1. Alertness
2. AMT4 (Age, DOB, Place, Year)
3. Attention (Months backwards)
4. Acute Change or Fluctuating Course
Guidelines & Evidence
Clinical Details
Section 1
When to Use
When to Use
Rapid delirium screening in the emergency department, acute medical units, and surgical wards.
Initial assessment of older adults presenting with acute confusion, falls, or functional decline.
Settings where a rapid (<2 minute) tool is needed without requiring special training.
Assessment of patients who are too drowsy or agitated to complete longer cognitive tests.
Why the 4AT?
The 4AT is designed for rapid clinical use. Unlike the CAM, it incorporates a brief cognitive test (AMT4) directly into the tool and explicitly scores untestable patients (who are often delirious). It is endorsed by SIGN and NICE guidelines as a primary delirium screen.
Section 2
Formula & Logic
Scoring
4 items scored: Alertness, AMT4, Attention, Acute Change.
Total score: 0–12
Score 0: Delirium or severe cognitive impairment unlikely
Score 1–3: Possible cognitive impairment
Score ≥ 4: Possible delirium +/- cognitive impairment
4 Items
1. Alertness
Normal (0), Mild sleepiness < 10s (0), Abnormal/Drowsy/Agitated (4)
2. AMT4
Age, DOB, Place, Current Year. No mistakes (0), 1 mistake (1), ≥2 mistakes/untestable (2)
Fluctuation or acute change from baseline over last 2 weeks? No (0), Yes (4)
Section 3
Pearls/Pitfalls
Untestable Patients Are Scored
A major advantage of the 4AT is that patients who are too drowsy to answer questions or attempt the months backwards test still receive scores (e.g., 2 points for untestable attention). This prevents the common problem of delirium being labelled "unable to assess".
Section 4
Next Steps
Management by Score
Score 0
Delirium unlikely. Reassess if clinical status changes.
Score 1–3
Possible cognitive impairment (e.g., dementia). Investigate baseline cognition. Delirium still possible if acute change is subtle.
Validation of the 4AT, a new instrument for rapid delirium screening: a study in 234 hospitalised older people.
Bellelli G et al. • Age Ageing.. 2014;43(4):496-502. Validation demonstrating 89.7% sensitivity and 84.1% specificity for delirium.
Section 6
Origins
MacLullich & Team
Developed by Alasdair MacLullich and colleagues in Edinburgh, Scotland. The 4AT was created to address the low routine screening rates for delirium in acute hospitals, providing a tool that requires no special training, incorporates cognitive testing natively, and can be completed in under 2 minutes.
