Delirium

Erin Wu, MD

Maya Narayanan, MD, MPH

What is the most effective strategy to prevent acute delirium in the hospital?

A multicomponent nonpharmacologic intervention that promotes mobility, maintains day-night cycle, optimizes nutrition and hydration, and improves vision/hearing impairment is the most effective method to prevent delirium.

This question was addressed in a prospective cohort study comparing 852 hospitalized elderly patients (age ≥70 years) who either received usual care or interventions related to six major delirium risk factors (Table 20.1).¹ Patients were matched according to age, sex, and baseline delirium risk (using a predictive model that defined high risk of delirium as 3-4 and intermediate risk as 1-2 of the following risk factors: visual impairment, severe illness, cognitive impairment, and high BUN:Cr ratio).

In the study group, a trained interdisciplinary team carried out the interventions (Table 20.1). All patients were evaluated daily for delirium using the digit span test, Mini-Mental State Examination (MMSE),
and Confusion Assessment Method (CAM). The primary outcome was delirium defined by CAM criteria. Secondary outcomes included the total number of days with delirium, delirium recurrence (≥2 episodes), and delirium severity (defined by the number of delirium characteristics present: symptoms fluctuation, inattention, disorganized thinking, and altered level of consciousness).

TABLE 20.1 Delirium Risk Factors and Corresponding Interventions

Delirium Risk Factor	Interventions
Cognitive impairment: MMSE score <20	Orientation with board listing names of care team members and day’s schedule; reorient to surroundings; cognitively stimulating activities (word games)
Sleep deprivation	Sleep protocol including offering warm milk or herbal tea, relaxing music, back massage; hospital unit noise reduction
Immobility	Ambulation or active range of motion exercises three times daily; minimizing immobilizing equipment (catheters, restraints)
Visual impairment (<20/70 visual acuity)	Glasses or magnifying lenses, large print books, fluorescent tape on call bell
Hearing impairment (≤6 of 12 on whisper test)	Portable amplifying devices, earwax disimpaction
Dehydration: BUN:Cr ratio ≥ 18	Encouragement of oral fluid intake
MMSE, Mini-Mental State Examination.

Delirium was less common in the study group (10% vs. 15%; OR 0.60, 95% CI 0.39-0.92; P = .02), as was the total number of days of delirium (105 vs. 161 days; P = .02). Groups did not differ with respect to delirium recurrence or severity.

These findings are supported by a 2015 meta-analysis that evaluated 4267 patients from across 11 studies (4 randomized controlled trials and 7 nonrandomized studies, most of which used nonmatched or historical controls).² All studies implemented nonpharmacologic
interventions addressing one or more of the following factors: cognition or orientation, mobility, hearing, sleep-wake cycle, vision, and/or hydration and examined the effect on delirium incidence. The meta-analysis showed that the odds of delirium was lower in the intervention group compared to controls (OR 0.47, 95% CI 0.38-0.58; P < .001).

Collectively, these results align with the 2010 National Institute for Health and Clinical Excellence (NICE) guidelines on delirium prevention, which recommend “assessment and modification of key clinical factors that may precipitate delirium, including cognitive impairment or disorientation, dehydration or constipation, hypoxia, infection, immobility or limited mobility, several medications, pain, poor nutrition, sensory impairment, and sleep disturbance.”³

You initiate a multicomponent nonpharmaceutical intervention that includes intravenous fluids, increasing daytime activity, and frequent reorientation. However, you receive a page overnight stating that your patient appears increasingly confused. His nurse is concerned that he is not responding to her questions appropriately and overhears him speaking out loud to an empty room. You assess the patient, who has a nonfocal neurological examination and no evidence of a fall. He is breathing comfortably, saturating well on 2 to 3 liters of supplemental oxygen. Laboratory testing does not reveal toxic-metabolic etiologies that could explain his confusion. You suspect acute delirium.

What instruments may be used to diagnose acute delirium in the hospital?

Among instruments, the CAM possesses the best evidence for diagnosing acute delirium in the inpatient setting.

The CAM was developed through a consensus building process by an expert panel and involves four “cardinal elements” (Table 20.2), with the diagnosis of delirium requiring the presence of features 1 and 2 as well as either 3 or 4. The CAM was prospectively validated through
a study conducted at two American academic medical centers⁴ that involved CAM testing for a total of 26 patients with delirium (based on psychiatrist diagnosis) and 30 without. There was high interobserver reliability for CAM scoring (kappa = 0.81-1.0). Across study sites (site 1/site 2), the CAM was found to have a sensitivity of 94/100%, specificity of 90/95%, positive predictive value of 91/94%, and negative predictive value of 90/100%.

TABLE 20.2 Elements of the CAM and Corresponding Questions

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