Delirium subtype identification and the validation of the Delirium Rating Scale--Revised-98 (Dutch version) in hospitalized elderly patients.

BACKGROUND: Delirium is the most common acute neuropsychiatric disorder in hospitalized elderly. The Dutch version of the Delirium Rating Scale-Revised-98 (DRS-R-98) appears to be a reliable method to classify delirium. The aim of this study was to determine the validity and reliability of the DRS-R-98 and to study clinical subtypes of delirium using the DRS-R-98.

METHODS: Patients received the Dutch version of the DRS-R-98, the Mini-Mental State Examination, the Confusion Assessment Method, and a clinical diagnosis of delirium according to DSM-IV criteria, and their relatives the Informant Questionnaire Cognitive Decline in the Elderly.

RESULTS: The DRS-R-98 validation cohort (n=65) consisted of 23 patients with delirium, 22 patients with dementia, and 20 non-psychiatric comparison patients. For the delirium subtype study, a second cohort comprising 54 delirious patients was investigated. Median DRS-R-98 scores significantly distinguished delirium from dementia and no psychiatric disorder. Inter-rater reliability (intra-class correlation 0.97) and internal consistency (Crohnbach's alpha 0.94) were high. Positive scores of DRS-R-98 item 4 (affect liability) and item 7 (motor agitation) predicted the presence of non-hypoactive delirium, with a specificity of 89% and a sensitivity of 57%.

CONCLUSION: The results show that the Dutch version of the DRS-R-98 is a valid and reliable measure of delirium severity and distinguishes patients with delirium from patients with dementia and comparison patients. Furthermore, the DRS-R-98 is able to exclude hypoactive delirium.