The Confusion Assessment Method (CAM)

Best Practices in Nursing Care to Older Adults from The Hartford Institute for Geriatric Nursing
New York University, College of Nursing
Issue Number 13, Revised 2007
Series Editor: Marie Boltz, MSN, APRN, BC, GNP
Managing Editor: Sherry A. Greenberg, MSN, APRN, BC, GNP
New York University College of Nursing

WHY: Delirium occurs in 25-60% of older hospitalized patients, and is associated with an increased risk of nursing home admission, increased costs, length of stay, mortality rates, functional decline, and increased use of chemical and physical restraints. Risk factors for delirium include older age, dementia, infection, severe illness, multiple co-morbidities, dehydration, psychotropic medication use, alcoholism, vision impairment, and fractures. Delirium is often unrecognized by clinicians. Therefore, patients should be assessed frequently using a standardized tool to facilitate prompt identification and management of delirium and underlying etiology.

BEST TOOL: The Confusion Assessment Method (CAM) was intended to provide a new standardized method to enable non-psychiatrically trained clinicians to identify delirium quickly and accurately in both clinical and research settings. Both a long and short version of the CAM are available. The long version is a comprehensive assessment instrument that screens for clinical features of delirium and correlates to DSM IV criteria. The short version includes only those four features that were found to have the greatest ability to distinguish delirium from other types of cognitive impairment. There is also a CAM-ICU version for use with non-verbal mechanically ventilated patients.

VALIDITY AND RELIABILITY: Both the CAM and the CAM–ICU have demonstrated sensitivity of 94-100%, specificity of 89-95% and high inter-rater reliability. Several studies have been done to validate clinical usefulness.

STRENGTHS AND LIMITATIONS: The CAM can be incorporated into routine assessment and has been translated into several languages. The CAM was designed and validated to be scored based on observations made during brief but formal cognitive testing, such as the Mini-Mental State Examination (or other brief mental status evaluations). There is a false positive rate of 10%. Training to administer and score the tool is necessary to obtain valid results. The tool identifies the presence or absence of delirium but does not assess the severity of the condition, making it less useful to detect clinical improvement or deterioration.

FOLLOW-UP: The presence of delirium warrants prompt intervention to identify and treat underlying causes and provide supportive care. Vigilant efforts need to continue across the healthcare continuum to preserve and restore baseline mental status.

MORE ON THE TOPIC: Best practice information on care of older adults: www.GeroNurseOnline.org. The Hospital Elder Life Program (HELP), Yale University School of Medicine. American Psychiatric Association. (2000). Diagnostic and statistical manual of mental disorders (4th ed.). Washington D.C.

Ely, E. Wesley, Margolin, R., Francis, J., May, L., Truman, B., Dittus, R, Speroff, T., Gautam, S., Bernard, G., & Inouye, S. (2001). Evaluation of delirium in critically ill patients: Validation of the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU). Critical Care Medicine, 29(7), 1370-1379.

Inouye, S.K. (2006). Delirium in older persons. NEJM, 354, 1157-65.

Inouye, S.K., Foreman, M.D., Mion, L.C., Katz, K.H., & Cooney, L.M. (2001). Nurses’ recognition of delirium and its symptoms: Comparison of nurse and researcher ratings. Archives of Internal Medicine, 161, 2467-2473.

Inouye, S., van Dyck, C., Alessi, C., Balkin, S., Siegal, A. & Horwitz, R. (1990). Clarifying confusion: The confusion assessment method. Annals of Internal Medicine, 113(12), 941-948.

Laurila, J.V., Pitkala, K.H., Strandberg, T.E., & Tilvis, R.S. (2002). Confusion assessment method in the diagnostics of delirium among aged hospital patients: Would it serve better in screening than as a diagnostic instrument? International Journal of Geriatric Psychiatry, 17(12), 1112-1119.

Rapp, C., Wakefield, B., Kundrat, M., Mentes, J., Tripp-Reimer, T., Culp, K., Mobily, P., Akins, J. & Onega, L. (2000). Acute confusion assessment instruments: Clinical versus research usability. Applied Nursing Research, 13(1), 37-45.

Schuurmans, M.J., Deschamps, P.I., Markham, S.W., Shortridge-Baggett, L.M. & Duursma, S.A. (2003). The measurement of delirium: Review of scales. Research and Theory for Nursing Practice: An International Journal, 17(3), 207-224.

The Confusion Assessment Method Instrument:

1. [Acute Onset] Is there evidence of an acute change in mental status from the patient’s baseline?

2A. [Inattention] Did the patient have difficulty focusing attention, for example, being easily distractible, or having difficulty keeping track of what was being said?

2B. (If present or abnormal) Did this behavior fluctuate during the interview, that is, tend to come and go or increase and decrease in severity?

3. [Disorganized thinking] Was the patient’s thinking disorganized or incoherent, such as rambling or irrelevant conversation, unclear or illogical flow of ideas, or unpredictable switching from subject to subject?

4. [Altered level of consciousness] Overall, how would you rate this patient’s level of consciousness? (Alert [normal]; Vigilant [hyperalert, overly sensitive to environmental stimuli, startled very easily], Lethargic [drowsy, easily aroused]; Stupor [difficult to arouse]; Coma; [unarousable]; Uncertain)

5. [Disorientation] Was the patient disoriented at any time during the interview, such as thinking that he or she was somewhere other than the hospital, using the wrong bed, or misjudging the time of day?

6. [Memory impairment] Did the patient demonstrate any memory problems during the interview, such as inability to remember events in the hospital or difficulty remembering instructions?

7. [Perceptual disturbances] Did the patient have any evidence of perceptual disturbances, for example, hallucinations, illusions or misinterpretations (such as thinking something was moving when it was not)?

8A. [Psychomotor agitation] At any time during the interview did the patient have an unusually increased level of motor activity such as restlessness, picking at bedclothes, tapping fingers or making frequent sudden changes of position?

8B. [Psychomotor retardation]At any time during the interview did the patient have an unusually decreased level of motor activity such as sluggishness, staring into space, staying in one position for a long time or moving very slowly?

9. [Altered sleep-wake cycle] Did the patient have evidence of disturbance of the sleep-wake cycle, such as excessive daytime sleepiness with insomnia at night?

The Confusion Assessment Method (CAM) Diagnostic Algorithm

Feature 1: Acute Onset and Fluctuating Course This 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) behavior fluctuate during the day, that is, tend to come and go, or increase and decrease in severity?

Feature 2: Inattention This 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: Disorganized thinking This feature is shown by a positive response to the following question: Was the patient’s thinking disorganized 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 [unarousable])

The diagnosis of delirium by CAM requires the presence of features 1 and 2 and either 3 or 4. CAM Instrument and Algorithim adapted from Inouye, S., van Dyck, C., Alessi, C., Balkin, S., Siegal, A. & Horwitz, R. (1990). Clarifying confusion: the confusion assessment method. Annals of Internal Medicine, 113(12), 941-948. Reprinted with permission. A SERIES PROVIDED BY The Hartford Institute for Geriatric Nursing EMAIL:hartford.ign@nyu.edu HARTFORDINSTITUTEWEBSITE:www.hartfordign.org GERONURSEONLINEWEBSITE: www.GeroNurseOnline.org Permission is hereby granted to reproduce, post, download, and/or distribute, this material in its entirety only for not-for-profit educational purposes only, provided that The Hartford Institute for Geriatric Nursing, College of Nursing, New York University is cited as the source. This material may be downloaded and/or distributed in electronic format, including PDA format. Available on the Internet at www.hartfordign.org and/or www.GeroNurseOnline.org. E-mail notification of usage to: hartford.ign@nyu.edu.