Volume 53, Issue 2 p. 312-318

A Chart-Based Method for Identification of Delirium: Validation Compared with Interviewer Ratings Using the Confusion Assessment Method

Sharon K. Inouye MD, MPH

Sharon K. Inouye MD, MPH

From the * Yale University School of Medicine, Departments of Internal Medicine Psychiatry

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Linda Leo-Summers MPH

Linda Leo-Summers MPH

From the * Yale University School of Medicine, Departments of Internal Medicine Psychiatry

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Ying Zhang MD, MPH

Ying Zhang MD, MPH

From the * Yale University School of Medicine, Departments of Internal Medicine Psychiatry

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Sidney T. Bogardus Jr. MD

Sidney T. Bogardus Jr. MD

From the * Yale University School of Medicine, Departments of Internal Medicine Psychiatry

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Douglas L. Leslie PhD

Douglas L. Leslie PhD

From the * Yale University School of Medicine, Departments of Internal Medicine Psychiatry

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Joseph V. Agostini MD

Joseph V. Agostini MD

From the * Yale University School of Medicine, Departments of Internal Medicine Psychiatry

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First published: 26 January 2005
Citations: 346
Sharon K. Inouye, MD, MPH, Yale University School of Medicine, 333 Cedar Street (DC013K), PO Box 208025, New Haven, CT 06520. E-mail: [email protected]

Funded in part by Grants RO1AG12551 and K24AG00949 (Dr. Inouye) from the National Institute on Aging and by in-kind support from the Claude D. Pepper Older Americans Independence Center at Yale University School of Medicine (#P30AG21342). Dr. Inouye is recipient of a Donaghue Investigator Award (#DF98-105) from the Patrick and Catherine Weldon Donaghue Medical Research Foundation.

Abstract

Objectives: To validate a chart-based method for identification of delirium and compare it with direct interviewer assessment using the Confusion Assessment Method (CAM).

Design: Prospective validation study.

Setting: Teaching hospital.

Participants: Nine hundred nineteen older hospitalized patients.

Measurements: A chart-based instrument for identification of delirium was created and compared with the reference standard interviewer ratings, which used direct cognitive assessment to complete the CAM for delirium. Trained nurse chart abstractors were blinded to all interview data, including cognitive and CAM ratings. Factors influencing the correct identification of delirium in the chart were examined.

Results: Delirium was present in 115 (12.5%) patients according to the CAM. Sensitivity of the chart-based instrument was 74%, specificity was 83%, and likelihood ratio for a positive result was 4.4. Overall agreement between chart and interviewer ratings was 82%, kappa=0.41. By contrast, using International Classification of Diseases, Ninth Revision, Clinical Modification, administrative codes, the sensitivity for delirium was 3%, and specificity was 99%. Independent factors associated with incorrect chart identification of delirium were dementia, severe illness, and high baseline delirium risk. With all three factors present, the chart instrument was three times more likely to identify patients incorrectly than with none of the factors present.

Conclusion: A chart-based instrument for delirium, which should be useful for patient safety and quality-improvement programs in older persons, was validated. Because of potential misclassification, the chart-based instrument is not recommended for individual patient care or diagnostic purposes.