A factor analytic study of the Delirium Rating Scale-Revised-98 in untreated patients with delirium

Existing factor analytic studies of symptoms of delirium are mostly based on small numbers of patients from specialized settings. This study thus sought to examine the factor structure of symptoms of delirium in a reasonably large sample of untreated patients referred to liaison psychiatric services of a multi-specialty hospital in north India, employing the more commonly used Delirium Rating Scale-Revised Version-1998 (DRS-R-98).

Patients (n=151) who met Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision criteria for delirium were assessed with the DRS-R-98 prior to starting treatment with psychotropics. A principal component analysis was carried out to determine the factor structure of the symptoms based on these ratings.

Unlike previous efforts, patients of this study were relatively younger (mean age 47 years), with mainly hyperactive delirium, and did not have comorbid dementia. Three factors which together explained 47.32 % of variance of symptoms were identified. A "global cognitive" factor including disturbances of orientation, attention, short- and long-term memory, and visuospatial ability accounted for 18.33% of the variance. A "sleep and motor symptoms" factor consisting of sleep-wake cycle disturbances; delusions; and perceptual disturbances including hallucinations, motor-agitation, inverse of motor-retardation, and affect-lability accounted for 16% of the variance. A "thought and language" factor comprising abnormalities in language and thought process, temporal onset, and fluctuation of symptoms explained 13% of the variance.

Thus, the current factor analysis not only confirmed the presence of three principal symptom dimensions of delirium (found in several previous studies) but also extended these findings to a broader group of patients usually referred to liaison psychiatric services.