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


METHODS
Prospective validation study.


METHODS
Teaching hospital.


METHODS
Nine hundred nineteen older hospitalized patients.


METHODS
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.


CONCLUSIONS
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.
Inouye
Sharon K
SK
Yale University School of Medicine, Department of Internal Medicine, New Haven, CT 06520, USA. sharon.inouye@yale.edu <sharon.inouye@yale.edu>
Leo-Summers
Linda
L
Zhang
Ying
Y
Bogardus
Sidney T
ST
Leslie
Douglas L
DL
Agostini
Joseph V
JV
D000368:Aged; D000369:Aged, 80 and over; D003693:Delirium / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007406:Interview, Psychological; D008297:Male; D008499:Medical Records; D011446:Prospective Studies; D011581:Psychological Tests; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index