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

Abstract

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. 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. 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%. 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.