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Diagnosing Delirium in Older Hospitalized Adults with Dementia: Adapting the Confusion Assessment Method to International Classification of Diseases, Tenth Revision, Diagnostic Criteria

Authors

  • Christine Thomas MD,

    Corresponding author
    1. Department of Psychiatry and Psychotherapy, University of Muenster, Muenster, Germany
    • Department of Geriatric Psychiatry, Centre of Psychiatry and Psychotherapy, Ev. Hospital Bielefeld-Bethel, Bielefeld, Germany
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  • Stefan H. Kreisel MD, MSc,

    1. Department of Geriatric Psychiatry, Centre of Psychiatry and Psychotherapy, Ev. Hospital Bielefeld-Bethel, Bielefeld, Germany
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  • Peter Oster MD,

    1. Bethanien-Hospital, Geriatric Centre, University of Heidelberg, Heidelberg, Germany
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  • Martin Driessen MD,

    1. Department of Geriatric Psychiatry, Centre of Psychiatry and Psychotherapy, Ev. Hospital Bielefeld-Bethel, Bielefeld, Germany
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  • Volker Arolt MD,

    1. Department of Psychiatry and Psychotherapy, University of Muenster, Muenster, Germany
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  • Sharon K. Inouye MD, MPH

    1. Aging Brain Center, Boston, Massachusetts
    2. Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
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Address correspondence to Dr. Christine Thomas, Abteilung für Gerontopsychiatrie, Klinik für Psychiatrie und Psychotherapie Bethel, Evangelisches Krankenhaus Bielefeld, Bethesdaweg 12, 33617 Bielefeld, Germany. E-mail: Christine.Thomas@evkb.de

Abstract

Objectives

To compare performance characteristics of the Confusion Assessment Method (CAM) algorithm for screening and delirium diagnosis with criteria for delirium from the International Classification of Diseases, Tenth Revision (ICD-10) and Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) in high-risk individuals.

Design

Prospective cohort study.

Setting

Academic geriatric hospital.

Participants

One hundred two individuals aged 80 to 100 hospitalized for acute medical illness.

Measurements

Complete CAM instrument (nine items), scored using the four-item CAM diagnostic algorithm. Criterion standard classification of delirium was rated independently according to expert consensus based on DSM-IV and ICD-10 criteria for delirium.

Results

In 79 hospitalized participants, the CAM performed well for delirium screening (delirium prevalence of 24% according to DSM-IV and 14% according to ICD-10). Of all CAM features, acute onset and fluctuating course are most important for diagnosis (area under the receiver operating characteristic curve (AUC) = 0.92 in DSM-IV and 0.83 in ICD-10). The CAM diagnostic algorithm had a sensitivity of 0.74, a specificity of 1.0, and an AUC of 0.88 compared with the DSM-IV reference standard and a sensitivity of 0.82, a specificity of 0.91, and an AUC of 0.85 compared with the ICD-10. Compared with the ICD-10, adding psychomotor change to the CAM algorithm improved specificity to 97%, but sensitivity fell to 55% (AUC = 0.96). Applying psychomotor change sequentially only to the group that the CAM algorithm identified as having no delirium improved sensitivity to 91% with specificity of 85% (AUC = 0.95).

Conclusion

Although the CAM diagnostic algorithm performed well against a DSM-IV reference standard, adding psychomotor change to the CAM algorithm improved specificity and diagnostic value against ICD-10 criteria overall in older adults with dementia and improved sensitivity and screening performance when applied sequentially in CAM-negative individuals.

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