Delirium among patients with and without dementia: does the diagnosis according to the DSM-IV differ from the previous classifications?

BACKGROUND: Different diagnostic criteria differ in their capacity to identify subjects as delirious. It is not known how DSM-IV classification, compared with the DSM-III, DSM-III-R, and ICD-10, identifies delirium among individuals with and without dementia and whether the symptom profiles differ between these two subgroups.
METHODS: A cross-sectional study was performed on patients (age > or = 70 years) in seven acute geriatric wards (n = 230) and in seven nursing-homes (n = 195) in Helsinki, Finland. Delirium was diagnosed according to the operationalized criteria according to the DSM-III, DSM-III-R, DSM-IV, and clinical criteria of ICD-10. Dementia was defined according to consensus judgment among three geriatricians with concise information including: prior dementia diagnoses, Clinical Dementia Rating Scale, operationalized criteria according to the DSM-IV, nurses and/or caregivers interviews, and the results of the brain CT/MRI and prior Mini-Mental State Examination scores, when available.
RESULTS: According to the DSM-III, DSM-IIIR, DSM-IV and ICD-10 criteria of delirium 22.7, 23.5, 25.9 and 14.9% of the demented, and 12.9, 13.5, 23.5 and 2.9% of the non-demented, respectively, were diagnosed as delirious. In stepwise logistic regression analysis clouding of consciousness, perceptual disturbances, and disorganized thinking were the most significant contributors to delirium diagnosis according to the DSM-IV among individuals with dementia, whereas perceptual disturbances, motor disturbances, and disorientation were the most significant contributors among those without dementia.
CONCLUSIONS: DSM-IV criteria of delirium identify new, often non-demented, subjects as being delirious, while ICD-10 is overly restrictive. The symptom profile of delirium was slightly different among individuals with and without dementia. Copyright 2004 John Wiley & Sons, Ltd.