Delirium (sometimes called 'acute confusional state') is a common clinical syndrome characterised by disturbed consciousness, cognitive function or perception, which has an acute onset and fluctuating course. It usually develops over 1 to 2 days. It is a serious condition that is associated with poor outcomes. However, it can be prevented and treated if dealt with urgently.

A person may already have delirium when they present to hospital or long-term care or it may develop during a hospital admission or residential stay in long-term care. Delirium can be hypoactive or hyperactive but some people show signs of both (mixed). People with hyperactive delirium have heightened arousal and can be restless, agitated and aggressive. People with hypoactive delirium become withdrawn, quiet and sleepy. Hypoactive and mixed delirium can be more difficult to recognise.

It can be difficult to distinguish between delirium and dementia and some people may have both conditions.

Older people and people with dementia, severe illness or a hip fracture are more at risk of delirium. The prevalence of delirium in people on medical wards in hospital is about 20% to 30%, and 10% to 50% of people having surgery develop delirium. In long-term care the prevalence is under 20%. But reporting of delirium is poor in the UK, indicating that awareness and reporting procedures need to be improved.

There is a significant burden associated with this condition. Compared with people who do not develop delirium, people who develop delirium may:

  • need to stay longer in hospital or in critical care

  • have an increased incidence of dementia

  • have more hospital-acquired complications, such as falls and pressure sores

  • be more likely to need to be admitted to long-term care if they are in hospital

  • be more likely to die.

This clinical guideline describes methods of preventing, identifying, diagnosing and treating delirium. In particular, the guideline focuses on preventing delirium in people identified to be at risk, using a targeted, multicomponent, non-pharmacological intervention that addresses a number of modifiable risk factors ('clinical factors').

If delirium is prevented, it should generate cost savings.

This guideline does not cover children and young people (younger than 18 years), people receiving end-of-life care, or people with intoxication and/or withdrawing from drugs or alcohol, and people with delirium associated with these states.

  • National Institute for Health and Care Excellence (NICE)