Key messages
- Delirium is an acute, fluctuating disturbance of attention, awareness and cognition; it is a medical emergency with substantial morbidity and mortality.
- Around 1 in 6 acute‑care in‑patients will be delirious at any one time and prevalence rises to >50 % in critical care. Early recognition halves downstream complications.
- Multicomponent, non‑pharmacological prevention bundles are the single most effective intervention; drug therapy is reserved for severe distress or danger.
- The 4AT is now the preferred bedside screening tool in the UK (2 minutes; no special training), and is embedded in NICE CG103 and national audit standards.
1. Definition and clinical impact
The DSM‑5 and NICE guideline CG103 define delirium as an acute change in consciousness and cognition with a fluctuating course, precipitated by an underlying medical disorder. Delirium is independently associated with a two‑ to four‑fold rise in 30‑day mortality, longer length of stay, increased institutionalisation and a heightened long‑term risk of dementia
2. Pathophysiology
Current models integrate neuro‑inflammation, impaired cortical connectivity and network dys‑synchrony triggered by systemic insults (sepsis, surgery, drug toxicity). Recent translational work implicates micro‑ and astro‑gliopathy as key amplifiers of the inflammatory cascade, opening avenues for disease‑modifying therapy
3. Predisposing and precipitating factors
Predisposing (baseline)
- Age ≥ 65 y, dementia or mild cognitive impairment
- Frailty, polypharmacy (>6 drugs), sensory impairment
- Previous delirium, stroke or Parkinson’s disease
Precipitating (acute)
- Infection, surgery or trauma
- Metabolic derangement (hypoxia, hypo‑/hyper‑glycaemia, electrolyte imbalance)
- Psychoactive drugs (benzodiazepines, anticholinergics, opioids)
- Environmental factors (sleep deprivation, restraints, transfer of care)
4. Clinical phenotypes
- Hyperactive (agitation, hallucinations) – easily recognised
- Hypoactive (withdrawn, drowsy) – frequently missed; carries the worst prognosis
- Mixed – oscillates between the two
5.Screening
As suggested by NICE guidelines, patient should be assessed using 4AT
assessment tool. After this, an underlying cause must sought out and a calm and
familiar environment should be ensured with adequate lighting. Orientation cues
(clock, calender etc) should be encouraged and patient’s response to treatment
should be monitored.
6. Managment plan
Take a full history and examine the patient carefully. Find out when the confusion started, how it has changed, how bad it is, and whether there were recent illnesses, new medicines, or changes in surroundings.
Do basic blood and urine tests. Check a full blood count (infection, anaemia), electrolytes and kidney/liver tests (metabolic problems), and a urine test to look for infection.
Order a brain scan when needed. A CT (or MRI if indicated) can help rule out stroke, bleeding, or other brain problems if the history or exam suggests it.
Review every medicine. Include prescriptions, over-the-counter drugs, and “as needed” meds. Look for drugs that can cloud thinking—especially those with anticholinergic effects.
Check the care environment. Is the patient getting their glasses/hearing aids? Are they sleeping at night? Are they over- or under-stimulated? Are restraints being used?
Consider hidden dementia. Some people have undiagnosed memory problems; delirium may be the first sign something was already wrong.
Look for simple physical triggers. Constipation with faecal impaction or not being able to pass urine (retention) can both cause or worsen delirium.
Assess and treat pain. Uncontrolled pain is a common and often overlooked trigger for delirium.
References
NICE (2023) ‘Delirium: Prevention, diagnosis and management in hospital and
long-term care. Available at http://www.nice.org.uk/guidance/cg103
Azizi, Z., O’Regan, N., Dukelow, T. et al. (2024) ‘Informal judgement of delirium status underestimates delirium prevalence: World Delirium Awareness Day point prevalence results from Ireland’, Delirium Communications, 4 June.
O’Connell, H. etal. (2025) ‘Outcomes associated with older patients who present or develop delirium in the emergency department: systematic review and meta‑analysis’, BMJ Open, 15(5):e095495.
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