Korean Version of the Delirium Rating Scale-Revised-98: Reliability and Validity

OBJECTIVE: The aims of the present study were 1) to standardize the validity and reliability of the Korean version of Delirium Rating Scale-Revised-98 (DRS-R98-K) and 2) to establish the optimum cut-off value, sensitivity, and specificity for discriminating delirium from other non-delirious psychiatric conditions. METHODS: Using DSM-IV criteria, 157 subjects (69 delirium, 29 dementia, 32 schizophrenia, and 27 other psychiatric patients) were enrolled. Subjects were evaluated using DRS-R98-K, DRS-K, Mini-Mental State Examination (MMSE-K), and Clinical Global Impression-Severity (CGI-S) scale. RESULTS: DRS-R98-K total and severity scores showed high correlations with DRS-K. They were significantly different across all groups (p=0.000). However, neither MMSE-K nor CGI-S distinguished delirium from dementia. All DRS-R98-K diagnostic items (#14-16) and items #1 and 2 significantly discriminated delirium from dementia. Cronbach's alpha coefficient revealed high internal consistency for DRS-R98-K total (r=0.91) and severity (r=0.89) scales. Interrater reliability (ICC between 0.96 and 1) was very high. Using receiver operating characteristic analysis, the area under the curve of DRS-R98-K total score was 0.948 between the delirium group and all other groups and 0.873 between the delirium and dementia groups. The best cut-off scores in DRS-R98-K total score were 18.5 and 19.5 between the delirium and the other three groups and 20.5 between the delirium and dementia groups. CONCLUSION: We demonstrated that DRS-R98-K is a valid and reliable instrument for assessing delirium severity and diagnosis and discriminating delirium from dementia and other psychiatric disorders in Korean patients.