Table 1

The confusion assessment method (CAM) diagnostic algorithm2

The diagnosis of delirium by CAM requires the presence of features 1 and 2 and either 3 or 4
Feature 1: Acute onset and fluctuating courseThis feature is usually obtained from a family member or nurse and is shown by positive responses to the following questions: Is there evidence of an acute change in mental status from the patient's baseline? Did the (abnormal) behaviour fluctuate during the day—that is, tend to come and go, or increase and decrease in severity?
Feature 2: InattentionThis feature is shown by a positive response to the following question: Did the patient have difficulty focusing attention—for example, being easily distractible, or having difficulty keeping track of what was being said?
Feature 3: Disorganised thinkingThis feature is shown by a positive response to the following question: Was the patient's thinking disorganised or incoherent, such as rambling or irrelevant conversation, unclear or illogical flow of ideas, or unpredictable switching from subject to subject?
Feature 4: Altered level of consciousness This feature is shown by any answer other than “alert” to the following question: Overall, how would you rate this patient's level of consciousness? (alert (normal), vigilant (hyperalert), lethargic (drowsy, easily aroused), stupor (difficult to arouse) or coma (unrousable))