Confusion Assessment Method (CAM)

A patient-based delirium assessment

About the CAM

  • Most widely used delirium assessment
  • The Confusion Assessment Method has undergone extensive validation across different clinical settings. Its short-form contains 4 features.
  • The presence of these features is determined by the rater while performing a bedside cognitive test (eg, modified Mini-Cog, Digit Span test).

4 Features of the CAM Algorithm

FEATURE 1: Altered mental status or fluctuating course

Feature 1—altered mental status or fluctuating course—is obtained from a collateral historian (eg, family member, caregiver) who knows the patient’s baseline cognition. Because ~40% of older ED patients may not have a family member or caregiver available in the ED, they may need to be contacted by phone. Fluctuations in mental status can also be observed during the patient’s evaluation.

FEATURE 2: Inattention

Feature 2—inattention. Patients who are inattentive are easily distractible to irrelevant stimuli and can have difficulty maintaining a conversation. Inattentive patients may also fall asleep during the interview, especially when disengaged. Questions often have to be repeated because the patient is inattentive.

FEATURE 3: Disorganized thinking

Feature 3—disorganized thinking. Patients with disorganized thinking exhibit incoherent thought processes. They may ramble, have irrelevant conversations, or have inappropriate responses to questions. They may also exhibit illogical tangential thoughts, circumstantiality, or illogical flow of ideas.

FEATURE 4: Altered level of consciousness

Feature 4—altered level of consciousness—is a patient who is drowsy, lethargic, anxious, restless, or agitated.

A patient is considered CAM-positive if they exhibit features 1 and 2, and either 3 and/or 4


Inouye SK. 2003; Boston, MA: Hospital Elder Life Program Accessed May 7, 2019. Last update September 8, 2014

Inouye SK, et al. Ann Intern Med. 1990;113(12):941–948


CAM, Confusion Assessment Method

ED, emergency department

MA, Massachusetts