diagnosis
Delirium is diagnosed exclusively on clinical grounds. The 5th edition of American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM-5) diagnostic criteria is commonly used as the standard (1).
In addition, the Confusion Assessment method is another useful tool to identify delirium at admission or throughout a patient's course of illness
- sensitivity ranges from 94% to 100% and specificity (90% - 95%) in hospitalized patients
- CAM takes up to 10 minutes to perform, hence in the emergency department, a shorter Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) may be more feasible (2)
Confusion Assessment Method (CAM)
- acute onset and fluctuating course
- is there evidence of an acute change in mental status from the patient's baseline? Did this behaviour fluctuate during the past day (that is, did it tend to come and go or increase and decrease in severity)?
- inattention
- does the patient have difficulty focusing attention; for example, being easily distracted or having difficulty keeping track of what was being said?
- disorganized thinking
- is the patient's speech disorganized or incoherent; for example, rambling or irrelevant conversation, unclear or illogical flow of ideas, or unpredictable switching from subject to subject?
- altered level of consciousness
- overall, how would you rate this patient's level of consciousness: alert (normal); vigilant (hyperalert); lethargic (drowsy, easily aroused); stupor (difficult to arouse); coma (unarousable)? (3)
Diagnosis of delirium requires a present/abnormal rating for criteria 1 and 2, and either 3 or 4
NICE recommendations:
- if indicators of delirium are identified, carry out a clinical assessment based on the Diagnostic and Statistical Manual of Mental Disorders criteria or short Confusion Assessment Method (short CAM) to confirm the diagnosis.
- in critical care or in the recovery room after surgery, CAM-ICU should be used. A healthcare professional who is trained and competent in the diagnosis of delirium should carry out the assessment. If there is difficulty distinguishing between the diagnoses of delirium, dementia or delirium superimposed on dementia, treat for delirium first.
- ensure that the diagnosis of delirium is documented both in the person's hospital record and in their primary care health record (4).
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