Associations of 4AT (Alertness, Abbreviated Mental Test-4, Attention and Acute change or fluctuating course)

Dr Thang S Han is Senior Lecturer at Royal Holloway, University of London and Endocrinologist at Ashford and St Peter’s NHS Foundation Trust. Here he discusses his Age and Ageing paper Associations of 4AT with mobility, length of stay and mortality in hospital and discharge destination among patients admitted with hip fractures.

Older individuals admitted to hospital with an acute condition such as a hip fracture are vulnerable to delirium. This condition is estimated to occur in up to a quarter of all acute admissions but it is often under-detected. The 4AT, comprising a battery of tests including Alertness, Abbreviated Mental Test-4, Attention and Acute change or fluctuating course, has been designed for rapid assessment of cognitive impairment, or delirium with or without cognitive impairment. The entire 4AT assessment takes only about two minutes to complete and does not require formal training.

The 4AT has recently been recommended by the Scottish Intercollegiate Guidelines Network (SIGN) for use as a screening tool to identify patients with probable delirium in the National Health Service in Scotland. Moreover, the National Institute for Health and Care Excellence (NICE) is currently monitoring results from a National Institute for Health Research study before considering recommendation. However, there is a paucity of data on health outcomes in relation to the 4AT tool due to its relative novelty and complex relationship with a number of factors leading to and/or co-existing with delirium throughout the course of an illness.

We examined the ability of the 4AT to predict, independent of the presence or absence of delirium: mobility within one day after surgery for a hip fracture (an indication of rapid recovery); length of stay and mortality in hospital; as well as discharge destination for those admitted with hip fractures. The 4AT was performed within a day of hip surgery in 522 men and women with an average age of 84 years. A 4AT score of 0 meant unlikely delirium or severe cognitive impairment (reference group); a score of 1-3 suggested possible chronic cognitive impairment, without excluding the possibility of delirium; a score 4 or more suggested delirium with or without chronic cognitive impairment.

We observed that compared to individuals with a 4AT score of 0, those with a 4AT score of 4 or more had 2.5- to 3.5-fold increases in risks of immobility, prolonged length of stay and mortality in hospital after their hip surgery, as well as being discharged to places where more care support is provided. These increased risks were independent of age, sex, nutritional status, co-existing chronic health conditions including dementia, and medications. Length of stay in hospital increased by three days for patients with a 4AT score of 1-3 and six days for patients with a 4AT score of 4 or more.

Findings from our study indicate that specialist assessment of the patient with delirium is required to identify and treat the cause and may involve geriatric medicine or frailty services and an integrated rapid response psychiatric liaison team in order to prevent and/or minimise adverse outcomes.