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4 A’s Test for Delirium Screening

Calculators  Neurology
4AT is a quick and effective tool utilized to detect delirium and cognitive impairment in older adults.
Regular 0
gentle sleepiness for less than normal after walking for 10 seconds 0
totally unusual 4
Birth date, age, place (building name or hospital name), present year
No mistakes 0
1 mistake 1
>=2 mistakes or untestable 2
Ask patient to list months in reverse order, starting at December
Lists >=7 months correctly 0
Starts but mention <7 months, or decline to start 1
Untestable (cannot start because drowsy, distracted, ill) 2
Acute change or fluctuating course
Notable variation or mental health status changed within the last 2 weeks and still predominant in the last 24 hours
No 0
Yes 4


Measured Factor
4AT / 4A's score
Measured Factor Disease
  • Delirium
  • Cognitive impairment
Measured Factor Detail
The 4 A's score increases rate of detection of delirium and cognitive impairment in acute general hospital settings specifically in geriatric patients. It is a rapid test that requires no special training and takes into account the assessment of severely agitated or drowsy patients while incorporating general cognitive screening. The 4AT has scoring rules to differentiate cognitive impairment from delirium. There are 4 factors used to calculate the score include:

1. Alertness
2. AMT4
3. Attention
4. Acute change or fluctuating course
Behavioral Neurologist
Body System
Measured Factor Low Impact
  • 4 AT score 0 suggests that delirium or severe cognitive impairment is unlikely to be present, but delirium may still be possible if information on acute change and fluctuation on mental status of patient is incomplete
  • A score of 1-3 suggests cognitive impairment and more detailed cognitive testing and informant history-taking are required
  • A score of 4 and above indicates presence of delirium and/or cognitive impairment
Measured Factor High Impact
  • A score of 4 and above indicates presence of delirium and/or cognitive impairment
  • It is not diagnostic but more detailed assessment of mental status may be required to reach a diagnosis

Result Interpretation

Ranges Ranges
  • Critical High: 4 and above
  • Normal: 0
  • Normal Adult Male: 0
  • Normal Adult Female: 0
  • Normal Geriatric Male: 0
  • Normal Geriatric Female: 0
Result High Conditions
  • Delirium
  • Cognitive impairment
False Positive
  • 4AT demonstrates excellent diagnostic accuracy
  • No false positive outcomes indicated
Test Limitations
The 4AT assessments are generally performed by experienced physicians, though no specific training in the 4AT is provided. Further research is needed to assess the ease of use of 4AT among other professional groups of varying levels of seniority. 

The clinical outcomes in relation to ‘possible delirium’ as assessed by the 4AT needs to be studied. This test does not assess the subtypes of delirium.

No consensus exists for the assessment of inattention and limited external validation has been performed in some small populations, including the acute stroke setting.


Study Validation 1
A study was conducted to validate the 4AT and 6-Item Cognitive Impairment Test (6-CIT) for emergency department dementia and delirium screening in attendees aged ≥70 years in a tertiary care hospitals. Trained researchers assessed 419 participants using the Standardised Mini Mental State Examination, Delirium Rating Scale-Revised 98 and informant questionnaire on cognitive decline in the elderly, informing ultimate expert diagnosis using Diagnostic and Statistical Manual of Mental Disorders (DSM-V) criteria for dementia and delirium. Another researcher blindly screened each participant, within 3 h, using index tests 4AT and 6-CIT. 

The results of the study demonstrated that 4AT had positive predictive value (PPV) 0.68 (95% confidence intervals: 0.58-0.79) and negative predictive value (NPV) 0.99 (0.97-1.00) for determination of delirium and for dementia detection, 4AT had PPV 0.39 (0.32-0.46) and NPV 0.94 (0.89-0.96) indicating 4AT accurately excludes delirium and dementia in older ED attendees.
References: 2
Study Validation 2
A prospective study was conducted in 257 patients admitted to the geriatric and orthogeriatric services of a tertiary teaching hospital. The participants aged 65 years and over were evaluated for delirium with the 4AT within 72 h of admission. The diagnosis of delirium was made separately by expert assessors, responsible for the participant's clinical care, blinded to the 4AT score, within 30 min of the 4AT assessment using the DSM 5 criteria and the Confusion Assessment Method. The sensitivity and specificity of the 4AT were reported to be 87% and 80%, respectively, in detecting delirium overall, 86% and 71% in people with probable dementia and 91% and 71% for non-English speaking participants.

The results of the study depicted that 4AT is a sensitive and specific screening tool for delirium in geriatric inpatients, including those with probable dementia or who are non-English speaking.
References: 3
Study Validation 3
A consecutive cohort study conducted in 500 patients with mean age 83 years  admitted to a geriatric medical assessment unit of an urban teaching hospital. Reference assessments were clinical diagnosis of delirium performed by elderly care physicians. Routine screening tests used were: Abbreviated Mental Test (AMT-10, AMT-4), 4 A's Test (4AT), brief Confusion Assessment Method (bCAM), months of the year backwards (MOTYB) and informant Single Question in Delirium (SQiD) to evaluate the test accuracy. The short screening tools such as AMT-4 or MOTYB have good sensitivity for definite delirium, but poor specificity; these tools may be reasonable as a first stage in assessment for delirium.

The 4AT is feasible and appears to perform well with good sensitivity and reasonable specificity.
References: 4
Study Additional 1
A prevalence study was conducted which included 108 acute and 12 rehabilitation wards in Italy. Delirium was detected using the 4-AT and motor subtypes were measured with the Delirium Motor Subtype Scale (DMSS). A multinomial logistic regression was used to determine the factors associated with delirium subtypes.

The study shows that hypoactive delirium is the most common subtype among hospitalized older patients. Specific clinical features were associated with different delirium subtypes. The use of standardized instruments can help to characterize the phenomenology of different motor subtypes of delirium.
References: 5
Study Additional 2
A prospective cohort study was conducted to determine whether emergency department (ED) length of stay before ward admission is associated with incident delirium in older adults. On ED admission, individuals underwent standardized evaluation of comorbidity (Cumulative Illness Rating Scale), cognitive impairment (Short Portable Mental Status Questionnaire), functional independence (activities of daily living, instrumental activities of daily living), pain (Numeric Rating Scale), and acute clinical conditions (Acute Physiology and Chronic Health Evaluation II). During the first 3 days after ward admission, the presence of delirium (defined as ≥1 delirium episodes within 72 hours) was assessed daily using a rapid assessment for delirium (4AT scale).

ED length of stay longer than 10 hours was associated with greater risk of delirium in hospitalized older adults, after adjusting for age and cognitive impairment.
References: 6
Study Additional 3
A retrospective study  evaluated 102 acute stroke patients in Stroke Units of San Martino Hospital (Genova, Italy) to diagnose delirium with clinical criteria, first by a neurologist without a formal training in DSM-V criteria and after training. Further 100 new acute stroke patients were enrolled  who underwent screening for delirium using 4AT scale and DSM-V criteria.

In the first phase, DSM-V criteria training significantly increased the ability to capture delirium (5 vs. 15%).

In the second phase, the 4AT was used for delirium screening revealing a 52% of cases of delirium, the same observed by the consensus diagnosis of two senior neurologists (that was 50%). Also, the use of 4AT scale allowed to capture post-stroke delirium as well as the consensus diagnosis by two neurologists. 

The identification of post-stroke delirium is not an easy task and requires both formal training in DSM-V criteria as well as the application of brief scales, such as the 4AT.
References: 7


Giuseppe Bellelli
Medicina e Chirurgia, 1988
Geriatric physician at the Azienda Ospedaliera San Gerardo in Monza, Italy and an associate professor in the department of medicine and surgery at the Università degli Studi di Milano-Bicocca, Azienda Ospedaliera San Gerardo Monza, Italy
Research Interests: Research on aging, delirium, and behavioral and psychotic symptoms of dementia (BPSD)
Alessandro Morandi
Department of Rehabilitation of the Fondazione Teresa Camplani (Cremona, Italy), Geriatric Consultant
Research Interests: Delirium, dementia and comorbid delirium and dementia
Guided various research studies on delirium in critically ill patients and rehabilitation settings


  1. 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; 43:496-502
  2. O'Sullivan D, Brady N, Manning E, O'Shea E, O'Grady S, O 'Regan N, Timmons S. Validation of the 6-Item Cognitive Impairment Test and the 4AT test for combined delirium and dementia screening in older Emergency Department attendees. Age Ageing. 2017; Sep 1:1-7
  3. De J, Wand AP, 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.
  4. Hendry K, Quinn TJ, Evans J, Scortichini V, Miller H, Burns J, Cunnington A, Stott DJ. Evaluation of delirium screening tools in geriatric medical inpatients: a diagnostic test accuracy study. Age Ageing. 2016; 45:832-837
  5. Morandi A, Di Santo SG, Cherubini A, Mossello E, Meagher D, Mazzone A, Bianchetti A, Ferrara N, Ferrari A, Musicco M, Trabucchi M, Bellelli G; ISGoD Group. Clinical Features Associated with Delirium Motor Subtypes in Older Inpatients: Results of a Multicenter Study. Am J Geriatr Psychiatry. 2017; 25:1064-1071
  6. Bo M, Bonetto M, Bottignole G, Porrino P, Coppo E, Tibaldi M, Ceci G, Raspo S, Cappa G, Bellelli G. Length of Stay in the Emergency Department and Occurrence of Delirium in Older Medical Patients. J Am Geriatr Soc. 2016; 64:1114-9
  7. Infante MT, Pardini M, Balestrino M, Finocchi C, Malfatto L, Bellelli G, Mancardi GL, Gandolfo C, Serrati C. Delirium in the acute phase after stroke: comparison between methods of detection. Neurol Sci. 2017; 386:1101-1104.

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