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Printed on 6/29/2026
For informational purposes only. This is not medical advice.
The Confusion Assessment Method (CAM), developed by Inouye et al. in 1990, is the most widely used bedside screening tool for delirium. It assesses four features: (1) acute onset and fluctuating course, (2) inattention, (3) disorganized thinking, and (4) altered level of consciousness. Delirium is diagnosed when Features 1 AND 2 are present, PLUS either Feature 3 OR Feature 4. The CAM has a sensitivity of ~94% and specificity of ~89% when used by trained clinicians. Delirium affects up to 50% of hospitalized elderly patients and is associated with increased mortality, prolonged hospital stay, and long-term cognitive decline. Quantify altered level of consciousness with [Glasgow Coma Scale](/tools/glasgow-coma-scale). Assess baseline frailty and functional status with [Clinical Frailty Scale](/tools/clinical-frailty) and [Katz ADL Index](/tools/katz-adl). For ICU delirium, track organ dysfunction with [SOFA Score](/tools/sofa-score). Metabolic causes of delirium — check [eGFR Calculator](/tools/egfr-calculator) and [Serum Osmolality](/tools/serum-osmolality).
Formula: CAM Positive = Feature 1 (acute onset) + Feature 2 (inattention) + Feature 3 (disorganized thinking) OR Feature 4 (altered consciousness).
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Feature 1 requires documenting that there has been an ACUTE change in mental status from the patient's baseline AND that this change FLUCTUATES over the course of the day. You cannot assess Feature 1 from a single point-in-time observation alone — you need collateral information. Sources for baseline and fluctuation assessment: family members or caregivers (ask: 'Is your parent normally confused like this? Does the confusion come and go?'), nursing staff who have observed the patient across multiple shifts, prior medical records documenting baseline cognitive status, comparison to the patient's admission cognitive status (in hospitalized patients). The MMSE, MoCA, or Brief Cognitive Status Examination can be used to objectify cognitive change if baseline scores are available. Key questions: 'Was this person confused yesterday but clearer this morning? Are they worse in the evenings?' Sundowning (worse in the evening) is a classic delirium fluctuation pattern.
Feature 2 — Inattention (REQUIRED for CAM positive): Test with standardized inattention assessments: (a) Serial 7s: ask patient to subtract 7 from 100 repeatedly (100, 93, 86...); (b) Months backwards: ask patient to recite months of the year in reverse order from December (more sensitive than serial 7s); (c) Digit span: read a sequence of random digits and ask patient to repeat them — normal is 5+ forward digits; (d) Vigilance test: read a random string of letters aloud at 1-second intervals (e.g., SAVEAHAART) and ask patient to tap when they hear the letter 'A' — count errors. Any difficulty with these tasks = Feature 2 present. Feature 3 — Disorganized thinking: Ask 4 simple yes/no questions (Will a stone float on water? Are there fish in the sea? Does 1 pound weigh more than 2 pounds? Can you use a hammer to pound a nail?) plus a 2-step command ('Hold up this many fingers' then transfer command to other hand without demonstration). 2+ errors = Feature 3 present. Feature 4 — Altered level of consciousness: Any level other than 'alert and normal' is positive: vigilant (hyperalert, startled by minor stimuli), lethargic (drowsy, easily aroused), stupor (difficult to arouse), or coma (cannot be aroused).
CAM POSITIVE (delirium present) = Feature 1 (acute onset + fluctuation) AND Feature 2 (inattention) AND EITHER Feature 3 (disorganized thinking) OR Feature 4 (altered consciousness) — ALL must be present in this combination. CAM NEGATIVE = delirium not detected by this assessment. If CAM positive: immediately initiate delirium workup — urinalysis and culture, CBC, BMP, TSH, LFTs, medication review (start/stop log), pain assessment, vital signs trend, oxygen saturation, review of recent procedures. Implement non-pharmacological delirium management (ABCDEF bundle): A = assess/manage pain; B = both SAT and SBT (spontaneous awakening and breathing trials); C = choice of analgesia/sedation (avoid benzodiazepines); D = delirium monitoring with CAM; E = early exercise/mobility; F = family engagement and empowerment. Avoid physical restraints — they worsen delirium. Reserve pharmacologic treatment (low-dose haloperidol or quetiapine) for severe hyperactive delirium with safety risk or patient distress — NOT for routine delirium management.
Hospitalist physicians, medical/surgical nurses, nursing staff
CAM should be used for systematic daily delirium screening in all hospitalized patients aged ≥65, particularly those in post-operative settings, orthopedic wards (hip fracture), cardiac care units, and any patient receiving opioids or sedative medications. The Joint Commission and NICE recommend systematic delirium screening. Studies show that without a structured screening tool like CAM, only 10–12% of delirium cases are detected by clinical staff. Institutionalizing daily CAM assessment as part of nursing documentation significantly increases detection rates and triggers appropriate non-pharmacological interventions (reorientation, early mobilization, sleep hygiene protocols, hearing aid/glasses provision).
Post-operative nurses, PACU nurses, surgical floor nurses, anesthesiologists
Post-operative delirium (POD) occurs in 14–56% of older adults after surgery, depending on procedure type and patient risk. CAM assessment beginning in the post-anesthesia care unit (PACU) and continuing daily for 5 days post-operatively is standard of care in high-risk settings. Triggers for immediate CAM assessment: sudden change in behavior, agitation, confusion, somnolence exceeding expected anesthesia effects, or family concern about mental status. CAM identification of post-operative delirium prompts immediate search for precipitants: inadequate pain control, urinary retention, electrolyte abnormalities, hypoxia, and medication interactions.
ICU physicians, critical care nurses, intensivists
The CAM-ICU is a validated adaptation of the standard CAM for non-verbal, mechanically ventilated ICU patients who cannot participate in the verbal assessments of the standard CAM. CAM-ICU replaces verbal inattention testing with a visual or auditory vigilance task (raise a hand when you hear the letter 'A') and assesses disorganized thinking with visual yes/no tasks and finger-count commands instead of verbal responses. CAM-ICU and CPOT (Critical Pain Observation Tool) form the core of the Society of Critical Care Medicine's PADIS (Pain, Agitation/Sedation, Delirium, Immobility, Sleep Disruption) guidelines, which recommend twice-daily delirium assessment in all ICU patients.
Emergency physicians, emergency nurses, geriatric emergency specialists
Delirium is present in 10–17% of older patients presenting to the emergency department, but is recognized by ED clinicians in fewer than 30% of cases without structured screening. A brief 3–4 minute CAM assessment should be incorporated into the ED triage or initial physician assessment for all patients ≥65 with altered behavior, confusion, or acute functional decline. CAM-positive patients require expedited medical evaluation, a safe and quiet environment, family notification, early mobilization if medically stable, and avoidance of unnecessary urinary catheters and physical restraints. ED delirium is associated with significantly worse 30-day outcomes.
All nursing staff, nursing assistants, care aides
Nursing staff are on the frontline of delirium detection and prevention. CAM assessment by trained nursing staff at each shift change allows early identification and documentation of delirium episodes. Non-pharmacological delirium prevention nursing interventions include: reorientation (clock, calendar, regular communication of date/location/care team), hearing aid and eyeglasses provision, early ambulation and physical therapy, day-night cycle preservation (lights on during day, quiet at night, minimize nighttime interruptions), regular toileting schedule to prevent urinary retention, adequate hydration and nutrition, and family presence and engagement. The HELP (Hospital Elder Life Program) is the most evidence-based delirium prevention program, built around these nursing interventions.
Multiple studies document that without a structured delirium screening tool, physicians and nurses miss 50–90% of delirium episodes. The most commonly missed subtype is hypoactive delirium, which presents with quiet, withdrawn, or drowsy behavior rather than classic agitation. Staff often interpret hypoactive delirium as 'resting comfortably' or appropriate sedation. Implementing mandatory CAM at every shift for high-risk patients (≥65, post-operative, receiving opioids or sedatives, known dementia) is the single most impactful intervention for delirium detection in hospitalized patients.
A landmark study by Inouye et al. (2014) found that CAM administered by untrained nursing staff without preceding structured cognitive testing had a sensitivity of only 47% — missing more than half of delirium cases. Proper CAM administration requires: completing a brief structured cognitive assessment before scoring (digit span, months backward, 4-question test), knowing how to score the fluctuation feature (requires collateral history), and being familiar with the difference between delirium and dementia. Train all staff who will administer CAM with a standardized training program (the CAM Training Manual is freely available from the Hospital Elder Life Program website).
Hypoactive delirium (quiet, withdrawn, sleepy, reduced activity) accounts for 25–50% of delirium presentations and has a significantly worse prognosis than hyperactive (agitated) delirium. Despite being more dangerous, hypoactive delirium is much less frequently recognized because it does not create behavioral problems. It is associated with higher rates of aspiration, pressure injuries, falls from unexpected unexpected movement, prolonged mechanical ventilation, and in-hospital mortality. CAM specifically detects hypoactive delirium through its inattention and altered consciousness criteria — even a quiet patient who fails the months-backward test and appears drowsy qualifies for a positive CAM.
Delirium during hospitalization has profound long-term consequences: (1) 10× longer length of stay; (2) 3× higher risk of functional decline to new disability; (3) independent risk factor for new dementia or acceleration of existing dementia over 3–5 years post-hospitalization; (4) higher risk of discharge to nursing home rather than home; (5) higher 1-year mortality. Framing delirium as a serious medical emergency — not a nuisance behavior — motivates appropriate urgency in detection and treatment. Communicate to families: 'Delirium is a serious medical condition that requires investigation and treatment, similar to how we would treat any other acute organ failure.'
Delirium is a symptom of an underlying medical problem, not a diagnosis itself. Always systematically search for precipitating causes using the 'I WATCH DEATH' mnemonic: Infection (UTI, pneumonia, sepsis, wound infection); Withdrawal (alcohol, benzodiazepines, opioids); Acute metabolic (electrolytes, glucose, renal failure, hepatic encephalopathy, acid-base); Trauma (head injury, post-operative); CNS pathology (stroke, meningitis, encephalitis, subdural hematoma); Hypoxia (hypoxemia, anemia, cardiac failure, pulmonary embolism); Deficiencies (B12, thiamine, folate); Endocrine (thyroid, adrenal, glucose); Acute vascular (MI, hypertensive emergency); Toxins/drugs (medication side effects, polypharmacy, anticholinergics, opioids); Heavy metals (lead, mercury, arsenic — rare, consider in specific contexts). Address every identified precipitant simultaneously — delirium is often multifactorial.
Benzodiazepines (lorazepam, midazolam, diazepam) are the most common iatrogenic cause of delirium in hospitalized older adults and should be avoided in delirium management (except for alcohol or benzodiazepine withdrawal delirium, where they are the treatment). Anticholinergic medications (diphenhydramine [Benadryl], promethazine, scopolamine, many first-generation antihistamines, tricyclic antidepressants) have high anticholinergic burden and frequently precipitate delirium in older adults. Before starting any medication in an older patient with delirium or at risk for delirium, check the Anticholinergic Cognitive Burden (ACB) Scale or Beers Criteria. Opioids are also deliriogenic but often necessary for pain management — minimize doses and choose lowest-deliriogenic options (morphine is more deliriogenic than hydromorphone; avoid meperidine entirely).
The Hospital Elder Life Program (HELP), developed by Inouye et al. at Yale, is the most evidence-based delirium prevention program. HELP uses trained volunteers and nursing staff to provide: cognitive stimulation (orientation, cognitively stimulating activities), daily mobilization and early physical therapy, vision and hearing adaptation (provide glasses and hearing aids), sleep enhancement (non-pharmacological sleep protocols — avoid sedating medications for sleep), oral hydration protocol, and therapeutic activities. HELP reduces delirium incidence by 33–40% in hospitalized older adults (RCT evidence). Implementing HELP in your institution has been shown to reduce costs, decrease falls, and shorten length of stay.
Patients with pre-existing dementia are 2–5× more likely to develop delirium during hospitalization compared to cognitively intact patients. Delirium superimposed on dementia (DSD) is also more difficult to detect because it is harder to identify acute change from an already impaired baseline. DSD is associated with dramatically worse outcomes: faster cognitive decline after the episode, higher short-term mortality, and higher rates of nursing home placement. Key to detecting DSD: establish detailed pre-illness cognitive baseline from family or prior records, and compare to current exam. Even subtle changes from a demented baseline (e.g., 'she's been more confused than usual') should trigger systematic CAM assessment.
CAM was developed by Inouye et al. (Ann Intern Med 1990) and validated against DSM-III-R criteria. Sensitivity 94–100%, specificity 90–95% in trained clinicians. Sensitivity drops to 47% without structured training (Inouye et al., Arch Intern Med 2001). CAM-ICU was developed for non-verbal patients by Ely et al. (JAMA 2001). The ABCDEF bundle for ICU delirium prevention: Devlin et al. (Crit Care Med 2018). HELP program evidence: Inouye et al. (NEJM 1999). MIND-USA trial: Girard et al. (NEJM 2018) — antipsychotics did not reduce delirium duration or improve outcomes.
The CAM result is either positive (delirium present) or negative (delirium not detected). A positive CAM requires Feature 1 (acute onset and fluctuating course) AND Feature 2 (inattention) to both be present, PLUS either Feature 3 (disorganized thinking) OR Feature 4 (altered level of consciousness). If this diagnostic algorithm is not fully met, the CAM is negative.
A positive CAM result indicates the patient is likely experiencing delirium, which is a medical emergency that requires immediate investigation for an underlying cause. Common precipitants include infection (urinary tract infection, pneumonia), medication effects (opioids, benzodiazepines, anticholinergics), metabolic derangements (electrolyte abnormalities, hypoglycemia, uremia), urinary retention, constipation, pain, and acute cardiac or neurologic events. A thorough history, physical examination, and targeted laboratory workup should be initiated promptly.
A negative CAM result does not completely exclude delirium, particularly hypoactive delirium, which presents with lethargy and decreased activity rather than the classic agitated, confused picture. Hypoactive delirium accounts for up to 50% of delirium cases and is frequently missed because patients appear quiet and compliant. If clinical suspicion remains despite a negative CAM, reassessment at a later time or use of a more sensitive tool (such as the CAM-ICU or 3D-CAM) should be considered.
Use the CAM as a bedside screening tool for delirium in any hospitalized patient, particularly older adults (65 years and older), who demonstrates acute changes in mental status, behavior, or cognition. Delirium affects up to 50% of hospitalized elderly patients and up to 80% of mechanically ventilated ICU patients, making routine screening essential. The CAM is recommended for daily screening in high-risk populations including postoperative patients, ICU patients, patients with hip fractures, patients with dementia, and those with multiple comorbidities.
The CAM is also useful in the emergency department for rapid delirium identification in confused older patients. It helps differentiate delirium from dementia, depression, and psychosis, each of which requires different management. Screening should be performed upon admission, after surgery, after any acute change in clinical status, and daily in high-risk patients. The assessment takes approximately 5 minutes when performed by a trained clinician.
The CAM's reported sensitivity of 94% and specificity of 89% were achieved when administered by trained clinicians following a structured cognitive assessment protocol. When used without formal training or without preceding cognitive testing (such as the Mini-Mental State Examination or digit span testing), sensitivity drops significantly — some studies report sensitivity as low as 46% among untrained nursing staff. Proper training in administering and scoring the CAM is essential for reliable results.
The standard CAM is designed for verbal, non-intubated patients who can participate in a brief cognitive assessment. It is not appropriate for mechanically ventilated patients, for whom the CAM-ICU (a modified version) should be used. It may also be difficult to apply in patients with severe aphasia, profound hearing loss, or pre-existing severe dementia, as these conditions can confound the assessment of inattention and disorganized thinking.
The CAM provides a dichotomous result (positive or negative) and does not quantify delirium severity. For severity assessment, the CAM-S (Confusion Assessment Method - Severity) or the Delirium Rating Scale should be used. The CAM also represents a single point-in-time assessment, and delirium is by definition fluctuating — a patient may screen negative at one time and positive hours later. Serial assessments throughout the day increase detection sensitivity.
For related assessments, see Clinical Frailty Scale, Katz ADL and Glasgow Coma Scale.
Disclaimer: This tool is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about your health.
April 21, 2026 · trust-baseline
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