Clinical Calculators

4AT (Rapid Clinical Test for Delirium)

Four items (alertness, orientation, attention, acute change) to detect possible delirium and cognitive impairment

4 items left

[1] Alertness

This includes patients who may be markedly drowsy (for example 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 the shoulder. Ask the patient to state their name and address to assist rating.

[2] AMT4 (Abbreviated Mental Test - 4)

Ask for age, date of birth, place (name of the hospital or building) and current year, and count the mistakes. For place, accept a reasonable identification of the setting (for example "the hospital"); the full formal name is not required. If the patient cannot give meaningful answers (for example because of drowsiness or impaired speech), choose "2 or more mistakes/untestable".

[3] Attention (months of the year backwards, starting at December)

Ask: "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. Naming 7 months or more correctly (December back to June) scores 0. Starting but naming fewer than 7 months, or refusing to start, scores 1. If the patient cannot start because of being unwell, drowsy or inattentive, it is untestable (2).

[4] Acute change or fluctuating course: evidence of significant change or fluctuation in alertness, cognition or other mental function (for example paranoia, hallucinations), arising over the last 2 weeks and still evident in the last 24 hours

This cannot be judged from observing the patient alone. Get information from one or more sources: ward staff who know the patient, family, carers, a referral letter or the case notes. Asking about hallucinations or paranoid thoughts can help, for example "Are you concerned about anything going on here?" If no informant is available but the course makes an acute change obvious (for example a patient who lived independently before admission is now drowsy), answer yes.

Cautions

  • Items [1] to [3] are rated solely on observation of the patient at the time of assessment. Item [4] needs information from one or more sources, such as people who know the patient, the case notes or a referral letter. Take communication difficulties (hearing impairment, dysphasia, lack of a common language) into account when carrying out the test and interpreting the score.
  • A patient who cannot be tested is still scored: items [2] and [3] are scored 2 as "untestable" (no patient with delirium is "unable to assess"). If both are untestable the total is 4, which suggests possible delirium.
  • A score of 4 or more is not a diagnosis of delirium; delirium is diagnosed from the whole clinical picture. A score of 0 does not definitively exclude delirium or cognitive impairment. In patients with severe dementia, items [2] and [3] can both score 2 and give 4, which lowers the specificity for delirium.
  • The official user guide states that altered alertness is more than 95% likely to be delirium in general hospital settings. The fluctuation in item [4] can occur in dementia alone, but marked fluctuation usually indicates delirium.
  • If the account given by the informant for item [4] cannot be relied on, consider it together with other information and clinical judgement.
  • Validation has been done mainly in hospital inpatients aged 65 or over and similar groups (the meta-analysis included only people aged 65 or over).
  • Adapted from the 4AT © 2011–2014 Alasdair MacLullich, Tracy Ryan and Helen Cash, licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Official and current version (version 1.2): https://www.the4at.com/ . This version has been modified. Changes: the instructions are shortened and reworded, and the items are reformatted into an input screen by codeblue-calc; the items, response options and scoring follow the official version, and the interpretation follows the official user guide. This screen is not the official 4AT and is not endorsed by its authors. The published validation evidence for the official 4AT should not be assumed to apply to this modified version. No warranty is given as to accuracy or fitness for purpose.

References

  1. MacLullich AMJ, Ryan T, Cash H. 4AT: Rapid Clinical Test for Delirium (4AT © 2011–2014 Alasdair MacLullich, Tracy Ryan and Helen Cash). Version 1.2 (October 2014). the4at.com. User guide and scoring. (User guide and scoring) https://www.the4at.com/userguide[Guideline]
  2. MacLullich AMJ, Ryan T, Cash H. 4AT: Notes on revisions. the4at.com. (Changes in versions 1.0, 1.1 and 1.2) https://www.the4at.com/notes-on-revisions[Guideline]
  3. Tieges Z, Maclullich AMJ, Anand A, et al. Diagnostic accuracy of the 4AT for delirium detection in older adults: systematic review and meta-analysis. Age Ageing. 2021;50(3):733-743. (Abstract) PMID: 33951145, DOI: 10.1093/ageing/afaa224[Review article]

Checked on: 2026-10-13

Disclaimer

This calculation is intended to support the judgment of healthcare professionals. Results are for reference only; decisions about diagnosis and treatment must be made by the responsible healthcare professional. The values you enter never leave your device.