Which patients are at risk of developing delirium?

Many older people who are in hospital or who live in a care home tend to have a complex mix of medical conditions. This complicates the task of identifying single risk factors, and multiple factors are thought to be the most common. One theory is that predisposing factors interact with precipitating factors. Predisposing factors are present at the time of hospital admission and reflect the person’s underlying vulnerability, whilst precipitating factors are those additional factors which contribute to the development of delirium (4,5).

These are shown below:

Risk factors or predisposing factors for developing delirium

• Older age > 70 years
• Severe illness
• Dementia
• Admission with electrolyte or endocrine disturbance
• Admission with infection
• Visual and hearing impairment
• Polypharmacy
• Depression in an older person
• Psychotropic drug use
• Alcohol abuse
• Previous stroke
• Sensory deprivation or overload

Precipitating factors for delirium

• Stroke
• Infection
• Pain
• Electrolyte and endocrine disturbance
• Physical restraints
• Psychotropic and anticholinergic drugs
• Opioids
• Trauma
• Organ Failure

4. Inouye SK, Viscoli CM, Horwits RI. 1993. A predictive model for delirium in hospitalized elderly medical patients based on admission characteristics. Annals of Internal Medicine 119: 474–81
5. Michaud L, Bula, C., Berney, A., Camus, V., Voellinger, R., Stiefel, F., Burnadn, B., the Delirium Guidelines Development Group. 2007. Delirium: Guidelines for general hospitals. Journal of Psychosomatic Research 62: 371–83