Confusion assessment method

Think: Mr. Williams is reported by the nursing staff to be agitated and unsteady on his feet. At times he tends to respond appropriately but on other occasions he has angry outbursts and does not listen when spoken to. On examination his speech is incoherent and he rambles in a disorganised way. There are no focal neurological deficits. Do you think he has delirium? Justify your answer?


  • What is a useful tool to use to detect delirium in hospitalised patients?
  • Does Mr. Williams meet the criteria for delirium using this tool?

The Confusion Assessment Method (CAM)

The CAM is a validated delirium diagnostic tool. It is considered the "gold standard" for detection of delirium(42). It is easy to use and can be completed in less than five minutes(26). It has been divided into two parts with the first being a cognitive assessment. Following the cognitive screen the second part being a diagnostic algorithm based on the four features of delirium is completed : The four features of delirium are:1) acute onset and fluctuating course, 2) inattention, 3) disorganised thinking and 4) altered level of consciousness. A positive diagnosis of delirium is made if the person has feature 1 & 2 plus either 3 or 4. The information gained from the cognitive assessment is used for the CAM. The following link provides more explicit training information on recognising delirium using the CAM (short version) (27) . For ICU patients who can't talk the ICU-CAM has been developed(46).

The Confusion Assessment Method Training Manual by S. Inouye (available via Hospital Elder Life website).

The Confusion Assessment Method-ICU Training Manual by W. Ely & B Truman Puu.

The CAM-ICU is a training manual for physicians, nurses and other health care professionals who wish to use the Confusion Assessment Method for the ICU (CAM-ICU).

The Confusion Assessment Method criteria

To have a positive CAM result, the patient must show:

  1. Presence of acute onset and fluctuating course and
  2. Inattention, plus either
  3. Disorganised thought processes, or
  4. Altered level of consciousness

Reference: Inouye SK, vanDyck CH, Alessi CA, Balkin S, Siegal AP, Horwitz RI. Clarifying confusion: The Confusion Assessment Method. A new method for detection of delirium. Ann Intern Med. 1990; 113: 941-948. Confusion Assessment Method: Training Manual and Coding Guide, Copyright 2003, Sharon K. Inouye, M.D., MPH. Not to be reproduced without permission. Instructions for correct usage available at the Hospital Elder Life Program (HELP) website Linked to another web site, or on request from Dr. Sharon Inouye.

The Confusion Assessment Method (CAM) flowchart

Click on the features and you will be taken to more detailed information on this topic.

CAM Diagnostic Algorithm (PDF file)