Table 1.

Risk factors for delirium in ICU patients

Host factors	Factors of critical illness	Iatrogenic factors
Age (older)	Acidosis	Immobilization (for example, catheters, restraints)
Alcoholism	Anemia	Medications (for example, opioids, benzodiazepines)
APOE4 polymorphism	Fever/infection/sepsis	Sleep disturbances
Cognitive impairment	Hypotension
Depression	Metabolic disturbances (for example, sodium, calcium, BUN, bilirubin)
Hypertension
Smoking	Respiratory disease
Vision/hearing impairment	High severity of illness

The table includes factors associated with delirium in both intensive care unit (ICU) and non-ICU studies. APOE4, apolipoprotein E₄; BUN, blood urea nitrogen.