4AT

The 4 'A's Test (4AT) is a bedside medical scale used to help determine if a person has positive signs for delirium.^[1][2] The test is designed to be used as a detection tool in general clinical settings, inpatient hospital setting outside of the Intensive Care Unit (ICU), or in the community. The 4AT is intended to be used by healthcare practitioners without the need for special training, and it takes around two minutes to complete.^[3] The test was first published online in 2011; the 4AT website provides downloads, and a guide to the test along with case examples.^[3] The 4AT is also available on the Android and iOS platforms, and as an online calculator.

The 4AT has been evaluated in multiple diagnostic test accuracy studies^[4][5] and it is used internationally in both clinical practice^{[6][7][8][9][10][11]} and research.^{[12][13][14][15]} It has been included in clinical guidelines and policy documents.^{[16][17][18][19][20][21]}

Emerging evidence shows that the 4AT can be implemented at scale in real-world clinical practice and that it shows positive score rates at similar levels to the expected delirium prevalence rates.^[22][23]

Summary

The 4AT has 4 parameters:

1. Alertness
2. Abbreviated mental test-4 (AMT4)
3. Attention (months backwards test)
4. Acute change or fluctuating course

The score range is 0–12, with scores of 4 or more suggesting possible delirium. Scores of 1-3 suggest possible cognitive impairment.

There are several indications of a positive score of 4 or more. Parameters [1] and [4] can each individually trigger a positive score. The rationale is that both altered arousal and acute change in mental functioning are highly specific indicators of delirium.^{[24][25][26][27]}

Parameters [2] and [3] provide embedded cognitive testing. These parameters can also yield an overall positive score for the 4AT: if [2] scores as 2 or more mistakes or if the patient is untestable, and with [3] the patient is untestable, then the combined score is 4, suggesting possible delirium. The rationale for allowing untestability to trigger an outcome of possible delirium is that many people with delirium are too drowsy or inattentive to undergo cognitive testing or interview.^[28][27] These scoring options additionally allow the 4AT to be completed in patients who are unable to provide verbal responses.

Psychometric properties

A review of data to December 2019 involving 17 studies reported a pooled sensitivity of 88% and a pooled specificity of 88% for delirium diagnosis.^[4] The current range of studies spans emergency department, medical, surgical and community settings.

Recommended use

The 4AT is intended to be used to assess for delirium on initial presentation with the patient, in transitions of care, and when delirium is suspected.^[29] Using the 4AT multiple times per day for monitoring for new onset delirium is not recommended because of the burden of repeated cognitive testing on patients and staff.^[30] However, it can be used 1-2 times per day for specified periods, e.g. peri-operatively. Additionally the 4AT is commonly used to monitor for recovery from active delirium. The 4AT is thus considered an episodic delirium test rather than a monitoring test.

Shorter, largely observational tests such as the National Early Warning Score - 2 (NEWS2),^[31] RADAR,^[32] the Delirium Observation Scale (DOS),^[33] the (Single Question in Delirium (SQiD),^[34] or the Nursing Delirium Screening Scale (Nu-DESC)^[35] are more suitable for ongoing routine monitoring for new delirium after admission to hospital (or in long-term care settings).^[36] A positive score in those tests generally then requires a more detailed assessment with a tool like the 4AT. This is an area of delirium practice which requires additional research.

The 4AT is one of several other delirium assessment tools in the literature.^[37] Each varies in its intended use (research, severity grading, very brief screening, etc.), completion time, need for training, and psychometric characteristics.^{[38][39][40][41][42]}

Languages

The 4AT has to date been translated into German, French, Italian, Spanish, Danish, Finnish, Turkish, Arabic, Norwegian, Thai, Cantonese, Putonghua, Russian, Korean and Icelandic.^[29]

References

External links

• 4AT test form