Delirium – Predisposing and Precipitating factors
Predisposing
| Predisposing factor | Relative Risk |
| Cognitive impairment | 2.1-4.2 |
| Dementia | 2.3-4.7 |
| Sensory impairment (vision or hearing) | 1.1-3.5 |
| Depression | 1.2-3.2 |
| Alcohol misuse | 1.4-5.7 |
| Age 75+ | 1.1-6.6 |
Other (per 2017 NEJM review) predisposing factors include: Male, age 65+, history of falls, malnutrition, psychoactive drugs, polypharmacy
Precipitating
| Precipitating factor | Relative Risk |
| Medications/Drugs (especially anticholinergics and psychoactive medications; check Beers list) | 2.9-4.5 |
| Physical restraints | 3.2-4.4 |
| Bladder catheter | 2.4 |
| Metabolic abnormality | 1.1-5.1 |
| Infection | 3.1 |
| Surgery | 3.5-8.3 |
| Trauma admit | 3.4 |
This list is not comprehensive. With our current model of precipitating factors, any medical insult or noxious stimuli may precipitate delirium in the patient with the right predisposing factors. In a young, functional, and otherwise healthy 24 year old, developing hyperosmolar hyperglycemic syndrome resulting in an ICU stay is a clear and obvious cause. On the other hand, in an older adult with severe dementia dependent on others for all activities of daily living, the precipitating cause (or more often causes) of their delirium may be as innocuous as an upper viral respiratory infection, constipation, or even for reasons we cannot detect.
While there are many approaches to determining the precipitating cause of delirium (like the DELIRIUM mnemonic, we would recommend using a systems based approach such as those used in the ICU to ensure a thorough approach.
*Note, Current delirium prediction models are poor and area of ongoing research!