Unit 2 – Risk Factors for Delirium

Section 1 – Introduction

Unit 1 covered the presentation of mental states so that we can respond quickly and appropriately to patients who come in with altered mental states.  However some patients develop altered mental states during their hospital stay.  Of the three mental states discussed delirium is preventable (to some extent) and reversible. So the remainder of the Units will focus on dealing with this common and important cause of altered mental state. This Unit is aimed at getting you to very quickly recognise those patients who may not have delirium now but have a high risk of developing it.  This is so important because there is promising research that shows delirium can be prevented if we understand how it comes about and make special effort with those at risk to prevent the factors that contribute to delirium (McCusker et al., 2003).  It we can avoid delirium the benefits for ourselves as carers and for the patients and relatives are huge.

Review Ted’s case notes again:

Try to find as many risk factors for delirium as you can and list them, (there are at least 4 risk factors).

Section 2

How many risk factors did you list?

1-4  – You missed quite a few risk factors that would leave Ted at risk of delirium. Please read further in this Unit to see a general description of risk factors

5-8 – Well done you have recorded quite a number of the risk factors but there are more. Please read further in this Unit to see a general description of risk factors

9 or 10  – Well done you have been very successful in identifying risk factors.  Please read further in this Unit to see a general description of risk factors to ensure your understanding of how they interact etc.

Section 3

Risk for the Development of Delirium

Some people are more vulnerable to delirium than others. There is general consensus that the development of delirium is multi-factorial. An understanding of the risk factors is vital to the management of delirium as vigilance in early detection and indeed prevention can lead to improved outcomes for patients.

Risk factors for delirium have been divided into predisposing and precipitating factors. Predisposing factors refer to characteristics present at admission and reflect the underlying vulnerability to delirium and precipitating factors are harmful factors that contribute to the development of delirium. Many studies conclude that predisposing risk factors contribute to greater vulnerability to delirium than do precipitating factors (Schuurmans et al., 2001).

Predisposing Factors

Elie et al (1998) systematically reviewed studies ranging in populations from medical, surgical and psychiatric. Previouspresence of dementiadepressionsensory impairmentabnormal serum sodiumalcohol abuse and poorer functional ability were strong risk factors.

Subsequent studies confirm pre-existing cognitive decline is an important risk factor (Martin et al., 2000, Gruber-Baldini et al., 2003, Lou et al., 2003, Schuurmans et al., 2003a, Bellelli et al., 2005, Freter et al., 2005, Gaudreau et al., 2005b). Poorer functional ability before admission (Marcantonio et al., 2003, Schuurmans et al., 2003a, Lou et al., 2004, Bellelli et al., 2005). Older age (Martin et al., 2000, Gruber-Baldini et al., 2003, Schuurmans et al., 2003a, Bellelli et al., 2005, Olin et al., 2005) and male gender (Gruber-Baldini et al., 2003, Schuurmans et al., 2003a, Bellelli et al., 2005) are also associated factors with delirium development. Also associated are, co-morbidity and severity of illness (Schuurmans et al., 2003a, Lou, 2004, Bellelli et al., 2005) and medication use, be that prescribed or non-prescribed (Schuurmans et al., 2003a, Freteret al., 2005).

While further research is required it can be said with some certainty that pre-existing cognitive decline, older age, greater medication use (high or changed), co-morbidity, sensory deficits and severity of illness are important predisposing risk factors for delirium development.

Section 4

In elderly medical patients, five independent precipitating factors have been found to predict the development of delirium: immobility, malnutrition, more than three medications added, use of bladder catheter and any iatrogenic event during hospitalisation (Inouye and Charpentier, 1996).

Research in surgical areas highlights prolonged waiting time for surgery (Edlund et al., 2001, Schuurmans et al., 2003a), type and duration of operation and anaesthetic and intraoperative blood loss (Gruber-Baldini et al., 2003, Schuurmans et al., 2003a, Olin et al., 2005). Prolonged waiting time for surgery maybe an important proxy for dehydration, poorer pain control, longer fasting times or innumerable factors that occur when waiting time for surgery is longer.

A large body of evidence exists associating drugs with a high anticholinergic burden (such as opiates, benzodiazapines and corticosteroids) with adverse consequences for the elderly (Tune et al., 2003) (Martin et al., 2000, Schuurmans et al., 2003a, Gaudreau et al., 2005a). With regards opiate use however, one study found that patients who receive less than 10mg of morphine sulphate equivalents per day were more likely to develop delirium than those who received more than this dose (Morrison et al., 2003). A study of delirium in cancer patients found that >2mg of Benzodiazepines, >15mg of corticosteroids or >90mg of opioids increases the risk of delirium (Gaudreau et al., 2005a). From this we can see that poorly controlled pain or over use of opiates can both be a cause of delirium. It is evident that medications use needs to be better understood so that patients are prescribed appropriate doses to control pain without causing delirium.

In the clinical case of Ted he had severe pain from osteoarthritis and his way of communicating this was to poor water on his knees. He had been taken off his non-steroidal anti inflammatory drug as they could have contributed to confusion however, when the cause of the delirium was discovered he was never put back on them so pain could have been a contributing factor to his delirium.

Identification of factors which predispose and precipitate delirium is key to its prevention. Inouye et al., (1993) developed a predictive model based on four risk factors (vision impairment, severe illness, pre-existing cognitive impairment and dehydration) which can be used on admission to identify those patients at greatest risk of developing delirium. This model for screening patients on admission is a simple predictive model based on four risk factors and is validated in a general medical setting.

Patients with baseline vulnerability for delirium are at risk for their whole admission which necessitates continued vigilance. If additional precipitating factors occur such as; malnutrition, increase or changed medications (particularly those with high anti-cholinergic burden), addition of invasive medical devises, pain, blood loss or dehydration staff should be aware of an increased likelihood of delirium development.

Section 5

In the clinical case of Ted he had severe pain from osteoarthritis and his way of communicating this was to poor water on his knees. He had been taken off his non-steroidal anti inflammatory drug as they could have contributed to confusion however, when the cause of the delirium was discovered he was never put back on them so pain could have been a contributing factor to his delirium.

Other factors you should pick up on include:

Predisposing

  • Age
  • Probable underlying dementia Deafness
  • Co-morbidities
  • Painful condition (osteoarthritis)
  • Some functional disability
  • Male gender

Precipitating

  • Poly-pharmacy
  • Commencement of anti-psychotics
  • Possible infection – see temp and pulse and trauma following bladder catheter removal
  • Pain – from catheter removal / osteoarthritis
  • Immobility
  • Not eating and drinking – possible fluid balance problems
  • Sensory overload – trauma of admission / strange surroundings and multiple interventions