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Case history

image A 76-year-old woman with known papillary thyroid cancer was admitted to the oncology ward following thyroidectomy. She had no significant past medical history. She became acutely confused and her family were concerned about her management on the ward. A urinary tract infection was subsequently diagnosed and she recovered with antibiotics. The nursing staff raised concerns about the future planned treatment with radioactive iodine should she have further episodes of confusion.

What is delirium and who is most at risk?

How is delirium diagnosed?

What are the common causes of delirium and how do these particularly relate to older patients with cancer?

How can delirium be prevented?

What measures should be implemented on wards when treating a patient with delirium?

What are the factors to consider in treating older patients with radioactive iodine who are at risk of delirium?

What is delirium and who is most at risk?

Delirium is the most common neuropsychiatric condition seen in oncology patients and is characterized by a rapid onset of fluctuating inattention and global cognition deficits. Often precipitated by multiple triggering factors, it can affect people at any stage of their life; however, it is more common in older people, those with pre-existing cognitive or functional impairment and those with multiple comorbidities. As the population ages, the number of older people with cancer who are at risk of delirium is rising. Delirium is associated with increased risk of death, institutionalization and cognitive decline, even in those without prior cognitive impairment, and its onset is associated with increasing healthcare costs.1 The incidence in patients with cancer has been reported to be between 8% and 85% depending on the setting.2 This is explained by the interaction of patient factors and precipitants of varying severity, whereby those with intrinsic risk factors for delirium (representing a vulnerable brain) may develop delirium with mild precipitants, whereas severe illness is often required in those whose brains are less vulnerable.

How is delirium diagnosed?

The diagnosis of delirium rests on clinical assessment and it should be distinguished from other neuropsychiatric disorders such as dementia, depression and psychosis. The gold standard is the application of DSM-5 criteria, but its use requires experience and time. Therefore, a number of different diagnostic tools have been developed, of which the Confusion Assessment Method3 (Table 15.1) is the most widely used and has been found to have the best diagnostic utility.

Table 15.1The Confusion Assessment Method.3 The diagnosis of delirium requires a present or abnormal rating for features 1 and 2 and for either 3 or 4.

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