A Comparison of the Severe Cognitive Impairment Rating Scale With the Mini-Mental State Examination and Delirium Rating Scale-Revised-98 for Delirium: A Cross-sectional Study

Background: Cognitive impairment including attention deficits, disorientation, memory impairment, language disturbance, and impaired visuospatial ability are core symptoms of delirium. The Severe Cognitive Impairment Rating Scale (SCIRS) was developed to assess cognition in patients with severe dementia, but may also be useful in elderly people with delirium. Objective: We investigated the use of the SCIRS to assess cognition in elderly patients with delirium. Methods: We recruited 147 participants, aged >65 years, referred for psychiatric consultation at a tertiary-care university hospital. The diagnosis and severity of delirium were assessed using the Korean version of the Delirium Rating Scale-Revised-98 (K-DRS-98). Cognitive function was assessed using the SCIRS and the Mini-Mental State Examination ( MMSE) in the Korean version of the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) Assessment Packet ( MMSE-KC). Results: There was a strong correlation of SCIRS scores with K-DRS-98 cognition domain (r = 0.796), severity scores (r = 0.742), total scores (r = 0.734), and the MMSE-KC (r = 0.905). Analysis of variance incorporating the severity of delirium suggested that while the MMSE showed a floor effect, the SCIRS could discriminate between moderate and severe delirium. Conclusion: The SCIRS is a useful instrument to assess cognitive function in elderly patients with moderate to severe delirium.