The Confusion Assessment Method for the ICU (CAM-ICU)

Issue #25 of General Assessment Series

WHY: The reported incidence of delirium among intensive care unit (ICU) patients ranges from 40-87%, with highest occurrence among older adults and those who receive mechanical ventilation. Delirium can be classified as either hypoactive (characterized by lethargy and less bodily movement), hyperactive (characterized by agitation and combativeness), or mixed (vacillating between hypo- and hyper- active forms). Delirium is associated with negative clinical outcomes (i.e., increased hospital length of stay, medical complications, physical restraint use, and prolonged neurocognitive deficits). Assessment of delirium using a clinically valid and reliable tool provides neurocognitive data necessary for the development of an appropriate treatment plan. One evidence-based, multi-component, interprofessional method of improving delirium assessment, prevention, and management of delirium is the ABCDEF Bundle.

BEST TOOL: Accurate delirium assessment cannot be obtained by informal bedside nurse-patient interaction. The CAM-ICU is an adaptation of the Confusion  Assessment Method by Inouye (1990), the most widely used instrument for diagnosing delirium by internists and non-psychiatric clinicians. The CAM-ICU is one of two monitoring tools recommended by the Society of Critical Care Medicine’s Clinical Practice Guidelines for the Management of Pain, Agitation, and Delirium in Adults Patients in the ICU.

TARGET POPULATION: The CAM-ICU should be used on all adults admitted to the ICU in order to promptly identify delirium and prevent negative outcomes.

VALIDITY AND RELIABILITY: The CAM-ICU is valid and shows high inter-rater reliability (kappa=0.79-0.96). Compared with a reference standard (psychiatrist) diagnosis of delirium, the CAM-ICU used by study nurses had sensitivities of 93-100% and specificities of 89-100%.

While not validated for use outside the ICU setting, the CAM-ICU can be used with a variety of ICU patients including those with medical, surgical, and neurobiologic conditions. A brief version for screening delirium is being tested for use in the Emergency Department. The Intensive Care Delirium Screening Checklist is an alternative method for delirium screening recommended by the Society of Critical Care Medicine. Other instruments that have been validated for screening for delirium in settings outside the ICU include the original CAM, the Delirium Rating Scale, the Memorial Delirium Assessment Scale, and the Nursing Delirium Screening Scale.

STRENGTHS AND LIMITATIONS: The CAM-ICU is rapid (<1 minute), easy to administer with minimal training, and has been translated into 26 different languages. It can be adapted for use with patients with hearing and visual disturbances and is easily reproducible. Staff training should include methods to assure reliability of assessment and to maintain performance after initial training. Although the CAM-ICU requires the use of special pictures, particularly for hearing impaired patients, materials and training manual can be downloaded from The CAM-ICU can also be accessed via MDCALC app.

FOLLOW-UP: Because delirium can occur at any time during critical illness, ICU patients should be monitored every shift for delirium onset and/or resolution of these symptoms.


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