Studies have reported that:
- older patients in surgical, palliative care and intensive care settings experience the highest rates of delirium1
- patients may come to hospital with delirium or may develop delirium while in hospital2
- patients are frequently discharged from hospital with persisting symptoms of delirium3
- delirium is preventable in 30–40 per cent of cases3.
Older people who experience delirium are at greater risk of functional and cognitive decline, falls, hospital acquired infections, pressure injuries and incontinence. Delirium can cause longer lasting cognitive impairments in patients after surgery and may ‘lead to permanent cognitive decline and dementia in some patients’3. Delirium is also associated with higher mortality and morbidity, increased length of hospital stay and admission to residential care4, 5.
Delirium can be caused by a range of factors
A range of factors affects an older person’s risk of developing delirium in hospital. Some factors are predisposing, that is they are related to characteristics of the person; some are precipitating, that is they are related to the person’s illness or the hospital environment. Delirium involves an interaction between the patient’s predisposing vulnerabilities, which puts them at greater risk when faced with precipitating factors.
Risk factors for delirium
* Comorbidity can be measured using the Charlson Comorbidity Index.
** BUN:creatinine ratio is the ratio of blood urea nitrogen (BUN) to serum creatinine and is used to determine acute kidney problems or dehydration. In Australia, it is referred to as urea:creatinine ratio.
1. Inouye, S.K., R.G.J. Westendorp, and J.S. Sacznski, Delirium in elderly people. The Lancet, 2014. 383: p. 911-922.
2. Travers, C., et al. Delirium in Australian Hospitals: A Prospective Study. Current Gerontology and Geriatics Research, 2013. 2013, 8.
3. Cole, M.G., Persistent delirium in older hospital patients. Curr Opin Psychiatry, 2010. 23(3): p. 250-254
4. Inouye, S., et al., Does delirium contribute to poor hospital outcomes? A three-site epidemiologic study. Journal of General Internal Medicine, 1998. 13(4): p. 234-42.
5. Wass, S., P.J. Webster, and R.N. Balakrishnan, Delirium in the elderly: a review. Oman Medical Journal, 2008. 23(3): p. 150-157.