Practice Easily Missed?

Delirium in older adults

BMJ 2013; 346 doi: (Published 09 April 2013) Cite this as: BMJ 2013;346:f2031
  1. Edison I O Vidal, assistant professor1,
  2. Paulo J F Villas Boas, associate professor1,
  3. Adriana P Valle, associate professor1,
  4. Ana Teresa A R Cerqueira, associate professor2,
  5. Fernanda B Fukushima, assistant professor3
  1. 1Internal Medicine Department, Universidade Estadual Paulista (UNESP), 18618-970 , Botucatu, SP, Brazil
  2. 2Neurology, Psychiatric and Psychology Department, Universidade Estadual Paulista (UNESP), 18618-970, Botucatu, SP, Brazil
  3. 3Anesthesiology Department, Universidade Estadual Paulista (UNESP), 18618-970, Botucatu, SP, Brazil
  1. Correspondence to: E I O Vidal eiovidal{at}
  • Accepted 4 January 2013

The daughter of an 80 year old woman with severely impaired vision from age related macular degeneration and diabetic retinopathy brought her mother to her primary care doctor, as she had been more apathetic and rejecting her meals in the past few days. Her daughter said there were times during the day when her mother looked almost her usual self, yet other times when she was confused and did not seem to be herself. Her doctor diagnosed delirium and referred the patient for assessment at the local emergency department.

What is delirium?

Delirium is a neuropsychiatric syndrome characterised by disturbances of cognition, attention, consciousness, or perception that develop over a short period of time (hours to days) with a fluctuating course.1 2 It usually results from the interaction of several precipitating factors (such as drugs, infections, metabolic disturbances, and myocardial infarction) and predisposing factors (such as old age, dementia, and multiple comorbidities).2 There are three subtypes of delirium, according to its psychomotor features: hyperactive, hypoactive, and mixed.

How common is delirium?

  • Among individuals aged 85 years and older living in the community the prevalence of delirium can be as high as 14%2

  • Among older people (aged 65 years and over), delirium usually occurs in 10-34% of those living in long term care facilities,3 in 30% of those in emergency departments,2 and in 10-42% during a hospital stay4

  • Delirium complicates 17-61% of major surgical procedures and occurs in 25-83% of patients at the end of life2 5

  • Despite the prevalence of delirium, healthcare professionals recognise only 20-50% of cases5

Why is delirium missed?

The fluctuating nature of the symptoms of delirium, its frequent overlap with dementia, the lack of routine formal cognitive assessment, its diverse presentations, and the misperception that little can be done to prevent or treat delirium contribute to its under-recognition.2 The hypoactive subtype of delirium (as our case was), the presence of pre-existing dementia, impaired vision, and being 80 years of age and older are independent risk factors for the under-diagnosis of delirium.6

Why does it matter?

Although delirium can be treated if dealt with urgently, failure to diagnose it can lead to poor outcomes and inappropriate treatment.1 In-hospital mortality rates for older patients with delirium range from 14.5% to 37%.4 After hospital discharge, a twofold independent increase in mortality risk was found to persist for about 12 months.3 Delirium is also associated with worse functional recovery after admission to hospital and with increased risk of being admitted to a care home.2 4 5 Direct costs attributable to delirium are extremely high—for example, in the United States these costs can exceed $150bn (£99bn; €117bn) a year.7 Additionally, the misdiagnosis of delirium can be associated with an eightfold increase in mortality risk.8

How is delirium diagnosed?

There are no diagnostic tests for delirium, which is diagnosed exclusively on clinical grounds.2 5 A systematic review concluded that the confusion assessment method is the bedside diagnostic instrument for delirium that is best supported by evidence, with positive and negative likelihood ratios of 9.6 and 0.16 respectively.9 In line with this method, diagnose delirium when the patient has (a) an acute change in mental status with a fluctuating course; (b) inattention; and either (c) disorganised thinking or (d) altered level of consciousness. Ideally score the confusion assessment method on the basis of observations made during brief cognitive tests (such as the mini-mental state examination). However, when scoring the confusion assessment method, also take into account any observations made away from formal cognitive tests (such as during consent, conversation, and physical examination). Ascertaining the presence of acute cognitive change with a fluctuating course (that is, when symptoms come and go or vary in intensity during the day) requires information from people acquainted with the baseline status of the patient and who have observed him or her over time. Document inattention if the patient is unable to focus or to shift attention according to external stimuli (for example, the patient is easily distracted or his or her focus darts around the room) or has difficulty reciting the days of the week backwards or raising a hand whenever a certain letter is spoken out of a list.5 Disorganised thinking is manifested by unclear flow of ideas, unpredictable changes in subject, rambling, or irrelevant conversation. Altered level of consciousness should be recorded if the patient is anything but alert (for example, hyperalert, lethargic, or comatose). An excellent interactive resource for learning how to use the confusion assessment method is available at

Distinguishing delirium from dementia and diagnosing delirium superimposed on dementia represent frequent clinical challenges.10 The determination of an acute change in the baseline pattern of mental functioning and behaviour of the patient is probably the most critical piece of information to be obtained. The finding of altered level of consciousness is also highly suggestive of delirium, even though its absence is not sufficient to rule out that diagnosis.10 Any difficulty distinguishing between the diagnoses of delirium, dementia, and delirium superimposed on dementia should lead to the safest and most reasonable treatment decision possible—that is, treat for delirium first.1

How is delirium managed?

Effective management of delirium requires approaching all modifiable predisposing and precipitating factors without delay.1 2 6 This includes removing unnecessary and potentially harmful drugs and treating underlying infections, volume depletion, and cardiorespiratory and metabolic disturbances. A common mistake is to deal with only a few of the most obvious precipitating factors (such as a urinary tract infection) while leaving unattended other major contributing factors. Various non-drug measures are also advocated for the treatment of delirium. Some of those measures involve frequently helping the patient to reorientate; reducing sensory impairment by providing spectacles and hearing aids; adopting early and frequent mobilisation programmes; discouraging the use of unnecessary tethers; and supporting an adequate sleep-wake cycle by, for example, coordinating schedules for obtaining vital signs and administering medications to provide uninterrupted periods of sleep.2 Reserve antipsychotic drugs for patients with hyperactive delirium whose agitation threatens their own safety or the safety of others despite the adoption of optimal non-drug interventions.1 2 11

Key points

  • Delirium can lead to poorer outcomes if untreated, yet is often missed, especially in patients aged ≥80 years, in the hypoactive subtype of delirium, and with pre-existing dementia or impaired vision

  • There are no diagnostic tests for delirium, which is diagnosed exclusively on clinical grounds

  • To increase the recognition of delirium healthcare professionals should routinely include a brief cognitive assessment during all encounters with older people

  • In line with the confusion assessment method, diagnose delirium when the patient has (a) an acute change in mental status with a fluctuating course; (b) inattention; and either (c) disorganised thinking or (d) altered level of consciousness

  • Treat all modifiable predisposing and precipitating factors without delay—for example, review medications, treat underlying conditions such as infection, reduce sensory impairment


Cite this as: BMJ 2013;346:f2031


  • This is one of a series of occasional articles highlighting conditions that may be more common than many doctors realise or may be missed at first presentation. The series advisers are Anthony Harnden, university lecturer in general practice, Department of Primary Health Care, University of Oxford, and Richard Lehman, general practitioner, Banbury. To suggest a topic for this series, please email us at easilymissed{at}

  • Contributors: EIOV and FBF had the idea for the article and drafted the first version of the manuscript. PJFVB and ATARC provided the specialist perspective about delirium among older adults, and APV provided the general practice perspective. All authors revised the manuscript critically for important intellectual content and approved the final version. EIOV is the guarantor.

  • Competing interests: All authors have completed the ICMJE uniform disclosure form at (available on request from the corresponding author) and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.

  • Provenance and peer review: Not commissioned; externally peer reviewed.

  • Patient consent not required (patient anonymised, dead, or hypothetical).