Confusion Assessment Method
Use when asked to administer, score, or explain the Confusion Assessment Method (CAM) — a bedside delirium screening algorithm (present/absent, not a numeric score) with a CAM-ICU variant for ventilated patients — grounded in FormExamples/form-examples; distinct from cognitive-assessment's chronic-impairment focus.
A structured, bedside delirium screening instrument that records four observational features of an acute confusional state and applies the validated CAM diagnostic algorithm to classify delirium as present or absent. The output is a boolean status derived from a fixed pattern of positive features, not a numeric sum, together with which features were positive and any safety-critical flags.
Developed by Inouye and colleagues (1990) to let non-psychiatric clinicians identify delirium quickly and reliably at the bedside, the CAM operates on observed cognitive and behavioural findings — collected during a brief structured interview and a formal attention test — rather than a laboratory result or self-report questionnaire. The CAM-ICU variant adapts the same four features for mechanically ventilated and other non-verbal patients using objective, non-verbal tasks.
Scoring: a diagnostic algorithm, not a sum
Four features, each present or absent: (1) acute onset and fluctuating course, (2) inattention, (3) disorganized thinking, (4) altered level of consciousness. Delirium is classified present when:
Feature 1 AND Feature 2 AND (Feature 3 OR Feature 4)Otherwise, delirium is classified absent — which does not exclude delirium if clinical suspicion remains.
What it covers
Assessor and encounter details (including CAM vs. CAM-ICU variant); patient identification with cognitive baseline; each of the four features with supporting evidence; motoric subtype and observations (hypoactive/hyperactive/mixed, hallucinations, sleep-wake disturbance); and result/disposition (classification, positive-feature set, suspected precipitants, safety flags, recommended actions).
Common pitfalls
- Treating a single negative CAM as ruling out delirium — delirium fluctuates by definition; a negative screen at one point doesn't exclude it, and at-risk patients should be re-screened regularly (e.g. once per shift).
- Missing hypoactive delirium — a quiet, withdrawn, drowsy presentation is frequently missed (it doesn't look like "confusion" in the popular sense) and carries a worse prognosis than the more obviously agitated hyperactive form.
- Stopping at "present" without a cause workup — a positive CAM is a prompt to search for reversible precipitants (pain, infection, nutrition, constipation, hydration, medication, environment), not an endpoint in itself.
- Confusing CAM with a cognitive-impairment screen — see Cognitive Assessment; CAM targets acute, fluctuating confusion, not chronic dementia-spectrum impairment.
Learn more
- Inouye S.K. et al. Clarifying confusion: the Confusion Assessment Method. Annals of Internal Medicine 1990; 113:941–8.
- FormExamples: confusion-assessment-method for the full implementation, CAM-ICU detail, and clinical references.
- Cognitive Assessment for the chronic-impairment counterpart.