3D-CAM: A New Delirium Screener

The link below takes to the Annals of Internal Medicine article on a new Confusion Assessment Method (CAM) derivative called the 3D-CAM [1].

3D-CAM: Derivation and Validation of a 3-Minute Diagnostic Interview for CAM-Defined Delirium: A Cross-sectional Diagnostic Test Study3D-CAM: Derivation and Validation of a 3-Minute Interview for Delirium | Annals of Internal Medicine.

Note the reference standard was a 45 minute evaluation including administration of the Montreal Cognitive Assessment (MoCA), medical records review, collection of collateral history from an informant, administration of the Geriatric Depression Scale, and a proxy-based screening questionnaire for dementia. The authors don’t state whether or not one of the clinicians conducting the reference standard evaluation was a psychiatrist or not. It looks like a geriatrician could do it.

I’ve never taken 45 minutes to assess delirium. I don’t have that kind of time. Typically I use the Mini-Cog with the basic short version of the CAM, which takes me less than 5 minutes generally.

CAM and Mini-Cog
CAM and Mini-Cog


SQiD Power
SQiD Power

If family members or friends are present, I ask them if their loved one seems more confused recently, essentially a quick and dirty form of the SQiD, which was about as good as the CAM in one study [2]. I always check the medical record quickly for the medication administration record, medical and surgical data including labs as well as the EKG interpretation, specifically the QTc interval in case I recommend injectable antipsychotic for management of agitation, and previous psychiatric and substance abuse history. I may also check for motor tone abnormalities.

The scale itself is copyrighted but you can view it on the Hospital Elder Life Program website after signing an agreement. I compared it with the Delirium Observation Screening Scale (DOSS), which is also copyrighted although anyone can Google it and have a peek at it.DOSS

The strength of the DOSS, which our nurses were trained to use here because they didn’t think they could manage the CAM, is that it allows for assessments across day, evening, and night shifts, which reduces the chances for fluctuations in delirium leading to missing the syndrome. The 3D-CAM is a spot screener but has cognitive assessment built in to the instrument to increase its sensitivity and specificity.

I don’t know if we need more scales so much as we need to be wired to suspect and systematically look for delirium in hospitalized patients, especially the demented elderly.

I also think we need to stop trying to “nursify” the scales so as to let doctors off the hook by expecting nurses to screen for it. Nurses had a thing or two to say about doctors responses to positive screens for delirium in a survey I ran a while back:Nurses survey delirium

I still suspect nurses would be reluctant to use the 3D-CAM. See what you think.


1. Marcantonio, E. R., et al. (2014). “3D-CAM: Derivation and Validation of a 3-Minute Diagnostic Interview for CAM-Defined DeliriumA Cross-sectional Diagnostic Test Study3D-CAM: Derivation and Validation of a 3-Minute Interview for Delirium.” Annals of Internal Medicine 161(8): 554-561.
Background: Delirium is common, leads to other adverse outcomes, and is costly. However, it often remains unrecognized in most clinical settings. The Confusion Assessment Method (CAM) is the most widely used diagnostic algorithm, and operationalizing its features would be a substantial advance for clinical care.Objective: To derive the 3D-CAM, a new 3-minute diagnostic assessment for CAM-defined delirium, and validate it against a clinical reference standard.Design: Derivation and validation study.Setting: 4 general medicine units in an academic medical center.Participants: 201 inpatients aged 75 years or older.Measurements: 20 items that best operationalized the 4 CAM diagnostic features were identified to create the 3D-CAM. For prospective validation, 3D-CAM assessments were administered by trained research assistants. Clinicians independently did an extensive assessment, including patient and family interviews and medical record reviews. These data were considered by an expert panel to determine the presence or absence of delirium and dementia (reference standard). The 3D-CAM delirium diagnosis was compared with the reference standard in all patients and subgroups with and without dementia.Results: The 201 participants in the prospective validation study had a mean age of 84 years, and 28% had dementia. The expert panel identified 21% with delirium, 88% of whom had hypoactive or normal psychomotor features. Median administration time for the 3D-CAM was 3 minutes (interquartile range, 2 to 5 minutes), sensitivity was 95% (95% CI, 84% to 99%), and specificity was 94% (CI, 90% to 97%). The 3D-CAM did well in patients with dementia (sensitivity, 96% [CI, 82% to 100%]; specificity, 86% [CI, 67% to 96%]) and without dementia (sensitivity, 93% [CI, 66% to 100%]; specificity, 96% [CI, 91% to 99%]).Limitation: Limited to single-center, cross-sectional, and medical patients only.Conclusion: The 3D-CAM operationalizes the CAM algorithm using a 3-minute structured assessment with high sensitivity and specificity relative to a reference standard and could be an important tool for improving recognition of delirium.Primary Funding Source: National Institute on Aging.

2. Sands, M., et al. (2010). “Single Question in Delirium (SQiD): testing its efficacy against psychiatrist interview, the Confusion Assessment Method and the Memorial Delirium Assessment Scale.” Palliative Medicine 24(6): 561-565.
In this study we address the research question; How sensitive is a single question in delirium case finding? Of 33 ‘target’ admissions, consent was obtained from 21 patients. The single question: ‘Do you think [name of patient] has been more confused lately?’ was put to friend or family. Results of the Single Question in Delirium (SQiD) were compared to psychiatrist interview (ΨI) which was the reference standard. The Confusion Assessment Method (CAM) and two other tools were also applied. Compared with ΨI, the SQiD achieved a sensitivity and specificity of 80% (95% CI 28.3—99.49%) and 71% (41.90—91.61%) respectively. The CAM demonstrated a negative predictive value (NPV) of 80% (51.91—95.67%) and the SQiD showed a NPV of 91% (58.72—99.77%). Kappa correlation of SQiD with the ΨI was 0.431 (p = 0.023). The CAM had a kappa value of 0.37 (p = 0.050). A further important finding in our study was that the CAM had only 40% sensitivity in the hands of minimally trained clinical users. Conclusion: The SQiD demonstrates potential as a simple clinical tool worthy or further investigation.

One thought on “3D-CAM: A New Delirium Screener

  1. And then there’s another sort of screen–the quick assessment descriptor of “Altered Mental Status” or “AMS,” which in the emergency room can point to other conditions like psychosis, intoxication, dementia, etc. I’ve always thought that AMS usually means the patient is delirious, which is why I don’t usually use the label AMS, https://thepracticalpsychosomaticist.com/2011/11/05/what-does-altered-mental-status-or-altered-mean-like-a-werewolf/

    Han, J. H., et al. (2014). “The Relationship Between a Chief Complaint of “Altered Mental Status” and Delirium in Older Emergency Department Patients
    La Relación entre el Motivo de Consulta Principal “Estado Mental Alterado” y el Delirium en los Pacientes Mayores en el Servicio de Urgencias.” Academic Emergency Medicine 21(8): 937-940.
    Background Altered mental status is a common chief complaint among older emergency department (ED) patients. Patients with this chief complaint are likely delirious, but to the authors’ knowledge, this relationship has not been well characterized. Additionally, health care providers frequently ascribe “altered mental status” to other causes, such as dementia, psychosis, or depression. Objectives The objective was to determine the relationship between altered mental status as a chief complaint and delirium. Methods This was a secondary analysis of a cross-sectional study designed to validate three brief delirium assessments, conducted from July 2009 to March 2012. English-speaking patients who were 65 years or older and in the ED for <12 hours were included. Patients who were comatose or nonverbal or unable to follow simple commands prior to the acute illness were excluded. Chief complaints were obtained from the ED nurse triage assessment. The reference standard for delirium was a comprehensive psychiatrist assessment using the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision criteria. Sensitivity, specificity, positive likelihood ratio (LR), and negative LR with their 95% confidence intervals (CIs) were calculated using the psychiatrist's assessment as the reference standard. Results A total of 406 patients were enrolled. The median age was 73.5 years old (interquartile range [IQR] = 69 to 80 years), 202 (49.8%) were female, 57 (14.0%) were nonwhite race, and 50 (12.3%) had delirium. Twenty-three (5.7%) of the cohort had chief complaints of altered mental status. The presence of this chief complaint was 38.0% sensitive (95% CI = 25.9% to 51.9%) and 98.9% specific (95% CI = 97.2% to 99.6%). The negative LR was 0.63 (95% CI = 0.50 to 0.78), and the positive LR was 33.82 (95% CI = 11.99 to 95.38). Conclusions The absence of a chief complaint of altered mental status should not reassure the clinician that delirium is absent. This syndrome will be missed unless it is actively looked for using a validated delirium assessment. However, patients with this chief complaint are highly likely to be delirious, and no additional delirium assessment is necessary.
    Introducción El estado mental alterado (EMA) es un motivo de consulta principal frecuente en pacientes mayores que consultan al servicio de urgencias (SU). Este motivo de consulta principal en estos pacientes corresponde con más frecuencia a delirium, pero según el conocimiento de los autores, esta relación no ha sido bien caracterizada. Además, los sanitarios frecuentemente relacionan EMA a otras causas, como la demencia, la psicosis o la depresión. Objetivos El objetivo fue determinar la relación entre EMA como motivo de consulta principal y el delirium. Metodología Análisis secundario de un estudio transversal diseñado para validar tres valoraciones breves de delirium, llevado a cabo de julio de 2009 a marzo de 2012. Se incluyeron los pacientes de habla inglesa que tenían 65 años o más de edad y que estuvieron menos de 12 horas en el SU. Se excluyeron los pacientes en coma o que tenían demencia en estadio terminal. Los motivos de consulta principales se obtuvieron de la valoración del triaje de enfermería del SU. El estándar de referencia de delirium fue una valoración psiquiátrica global usando los criterios revisados DSM-IV (Diagnostic and Statistical Manual of Mental Disorders, cuartra edición). Se calculó la sensibilidad, la especificidad, la razón de probabilidad positiva y la razón de probabilidad negativa con sus intervalos de confianza al 95% usando la valoración del psiquiatra como estándar de referencia. Resultados Se incluyeron un total de 406 pacientes. La mediana de edad fue de 73,5 años (rango intercuartílico: 69 a 80 años), 202 (50%) fueron mujeres, 57 (14%) de raza no blanca y 50 (12,3%) tuvieron delirium. Veintitrés pacientes (5,7%) de la cohorte tuvieron como motivo de consulta principal EMA. La presencia de este motivo de consulta principal tuvo una sensibilidad de un 38,0% (IC 95% = 25,9% a 51,9%) y una especificidad de un 98,9% (IC 95%= 97,2% a 99,6%). La razón de probabilidad negativa fue 0,63 (IC 95% = 0,50 a 0,78) y la razón de probabilidad positiva fue 33,82 (IC 95% = 11,99 a 95,38). Conclusiones La ausencia de un motivo de consulta de EMA no debería hacer pensara al clínico que el delirium está ausente. El diagnóstico de este síndrome se perderá a menos que se busque activamente usando un valoración validada de delirium. Sin embargo, los pacientes con EMA como motivo de consulta principal es más probable que padezcan delirium y que no sea necesaria una valoración de delirium adicional.


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