Factor structure and differential validity of the expanded brief psychiatric rating scale

The Brief Psychiatric Rating Scale (BPRS) is one of the most widely used measures in psychiatric outcome and clinical psychopharmacology research. To date, however research on the psychometric properties of the expanded version of the BPRS (BPRS-E) has been limited. An exploratory factor analysis (n = 360) using maximum likelihood extraction with oblimin rotation found a four-factor solution (Thought Disturbance, Animation, Mood Disturbance, Apathy) to underlie the BPRS-E. Furthermore, these factors were logical in nature and estimates of internal consistency were acceptable. A confirmatory factor analysis conducted on a second, independent sample (n = 280)found that for the five models currently available in the literature, the model developed herein provided the best fit to the data. Again, estimates of internal consistency were found acceptable. Finally, the four factors demonstrated appropriate differential validity with regards to both demographic variables and various psychiatric diagnoses.