Table 2.

Predisposing and precipitating risk factors in the general medical, post-operative, and ICU settings [10, 43, 54–60]

	General medicine	Additional operative risks	Additional ICU risks
Predisposing risk factors	Older age Low daily activity levels Immobility Sensory impairment Low levels of education Malnutrition Pre-existent cognitive impairment Frailty Comorbidities Alcohol consumption Visual/Hearing impairment	Cerebral disease Chronic diseases: renal, cardiac, hepatic, or pulmonary Alcohol/sedative-hypnotics addiction History of delirium/functional psychosis Depression Vitamin deficiency Seizures or porphyria	Higher illness severity Unexpected hospital admission
Precipitating risk factors	Acute medical illness Fractures Head injury Trauma Surgery Psychological stress Drug use/withdrawal Urinary catheterisation Longer hospital stay	Drug intoxication/anaesthesia Metabolic disturbance Hemodynamic disturbance Respiratory disorders Infection Acute cerebral disorder Alcohol/sedative withdrawal Intraoperative/post-operative: Sleep deprivation Immobilisation Restraints	Mechanical ventilation (and duration of ventilation) Sepsis Opioids Polypharmacy Circadian rhythm disruption Deep sedation Organ failure