3D-CAM - American Geriatrics Society

3D-CAM: Validation of a3-Minute Diagnostic Interview forCAM-defined DeliriumEdward R. Marcantonio, MD SMBeth Israel Deaconess Medical CenterHarvard Medical School, Boston MAAmerican Geriatrics Society National Meeting

Acknowledgements/ConflictsCo-Authors:• Long Ngo, PhD 1,3• Richard Jones, ScD 1,2,3• Kerry Palihnich 1• Margaret O’Connor, PhD 1,3• Paul Crane, MD MPH 4• Sharon Inouye, MD MPH 1,2,3• Funding:R01AG030618 fromthe National Instituteon Aging• No conflicts to report:The authors retainedfull autonomy incarrying out this workInstitutional Affiliations: 1. Beth Israel Deaconess Medical Center,2. Aging Brain Center, Institute for Aging Research, Hebrew SeniorLife,3. Harvard Medical School, 4. University of Washington

Background• Delirium: Common, Morbid, Costly– Under-recognition still a major problem• Confusion Assessment Method (CAM)*– Most widely used diagnostic algorithm (10X > DSM)– Assess 4 diagnostic features: does not specify items– Variation in assessment → variable results• Standardized interview:– CAM-ICU: non-verbal patients– No such interview for verbal patients*Inouye et. al, Ann Int Med, 1990

3D-CAM Derivation• Dataset: >4500 CAM assessments– 160 patient questions, cognitive tests, structuredobservations, 20-25 minutes to complete• Mapped items to 4 CAM diagnostic features*• Item Response Theory: most informative items†• Modeling: further reduce items, set thresholds• Final 3D-CAM: 21 items• Apply 3D-CAM: Sensitivity: 92%, Specificity 93%relative to 160-item assessment*Huang et. al., JAGS, 2012; †Yang et. al., BMC Res Methods, 2013

3D-CAM ContentsFeature 1: Acute change/fluctuation—3 patient questionsEx) Have you felt confused today?Feature 2: Inattention— 4 cognitive itemsEx) Tell me the days of the week backwardsFeature 3: Disorganized Thinking—3 cognitive itemsEx) Can you tell me what type of place this is?Feature 4: Altered LOC—2 Observations• 8 Addn’l Observation Items (optional)• 1 Caregiver acute change question (if needed)

Current Aims• Prospectively validate the 3D-CAM relative toa gold standard clinical delirium assessment– Subset analysis: dementia, mild cognitiveimpairment (MCI)• Measure 3D-CAM inter-rater reliability

Subject Recruitment• Acutely hospitalized older adults• Aged 75 years or older• General medicine service• Large teaching hospital• Exclusions:– Non-English speaking– Imminently terminal illness– No informed consent (patient or caregiver)

Gold Standard Assessment• For delirium and dementia/MCI• Patient evaluation– History– Physical/neurological exam– Cognitive testing (MOCA)• Nurse and family interviews (AD-8)• Medical record review• Performed by experienced clinicians• Final diagnoses adjudicated by panel– Assessor, Study PI, Co-I

3D-CAM Testing• Performed within 2 hours gold standard– All testing between 11 AM-2PM• Trained RA’s blinded to gold standard results• All patients: 3D-CAM• Subset: second 3D-CAM (blinded to first)

Analysis• Validity: first 3D-CAM delirium determinationcompared to gold standard delirium diagnosis– Sensitivity, specificity– Stratified by dementia/MCI status• Reliability: two 3D-CAM results compared– Kappa statistic

Study SchematicGold StandardAssessment(N=201)3D-CAM 1(N=201)3D-CAM 2(n=100)Delirium DiagnosisValidityDelirium DeterminationReliabilityDelirium Determination

Study Population (N=201)Subject CharacteristicMean ± S.D., N(%),Median [IQR]Age (years) 84±5Female Gender 125 (62%)Delirium (Gold standard) 42 (21%)Dementia/MCI (Gold standard)DementiaMCI113 (57%)54 (27%)59 (30%)Duration of 3D-CAM (minutes) 3 [IQR 2,5]

DeliriumDiagnosis(- or +)Gold standard(-)Gold standard(+)3D-CAM(-)Validity3D-CAM(+)GoldStandardTotalsTestCharacteristic%, 95% C.I.150 9* 159 Specificity=150/15994% [91%,98%]2 40 42 Sensitivity=40/4295% [89%,100%]3D-CAM Totals 152 49 201*Of 9 3D-CAM “false positives”, 6 had sub-syndromal delirium

Validity: Subgroup AnalysisNormal baseline cognition• Sensitivity: 100% [87%,100%]• Specificity: 98% [94%,100%]Dementia/MCI• Sensitivity: 95% [87%,100%]• Specificity: 91% [84%,97%]

Inter-rater reliabilityDeliriumDiagnosis(- or +)3D-CAM 2(-)3D-CAM 2(+)3D-CAM 1Totals3D-CAM 1(-)3D-CAM 1(+)3D-CAM 2Totals74 1 754 21 2578 22 100Kappa Statistic=0.86 [0.74,0.98]

Methodological ConsiderationsLimitations• Cross-sectional study– Does not address repeatedadministration• Single hospital study• Medicine patients onlyStrengths• Large validation study• Challenge population– Very old– High prevalence dementia/MCI

Conclusions/Implications• 3D-CAM:– Structured interview for verbal patients– Assesses 4 CAM diagnostic features– Completed 3 minutes• Excellent validity relative to gold standard– Works well in patients with dementia/MCI• Excellent inter-rater reliability• Because of brevity and ease of use, 3D-CAMcould be important tool for improving deliriumcare, education, and research