4AT — Rapid Assessment for Delirium
Rapid bedside screening tool for delirium and cognitive impairment. Does not require special training.
How to use & interpret
The 4AT is a brief, widely-used bedside screen for delirium (and cognitive impairment) that needs no special training. It assesses alertness, a 4-item orientation test (AMT4), attention (reciting the months backwards), and whether there has been an acute change or fluctuating course.
A total of ≥4 suggests possible delirium (and/or cognitive impairment), 1–3 suggests possible cognitive impairment, and 0 makes delirium/significant impairment unlikely. It complements, but does not replace, a full delirium assessment and a search for the precipitating cause.
Score interpretation
4AT = 0: Delirium/cognitive impairment unlikely
→ No specific delirium intervention; continue monitoring; reassess if clinical deterioration
4AT 1–3: Possible cognitive impairment (not delirium)
→ Cognitive assessment (MMSE/MoCA); consider dementia workup; capacity assessment if needed
4AT ≥4: Possible delirium
→ Full delirium assessment; identify and treat precipitants (infection, medications, pain, constipation); non-pharmacological interventions; orientation; review drugs; consider psychiatry/geriatrics
Interpretation bands for the 4AT. Apply clinical judgement and local guidance.
Frequently asked questions
Does a 4AT ≥4 diagnose delirium?
It flags possible delirium and should trigger a full clinical assessment (DSM-5/CAM criteria) and a search for causes — it is a screening tool, not a diagnosis.
References
- Bellelli G, 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.
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Featured in these MRCEM clinical pathways
The 4AT is covered in detail — with RCEM/NICE evidence base, indications and pitfalls — in the following exam-focused pathways on our sister siteReviseMRCEM.
MRCEM Primary / Intermediate / OSCE candidates: each pathway includes exam-style questions, RCEM/NICE citations, and FAQ summaries.
Decision support only — verify against a current formulary, NICE, or your local guideline before clinical use.