Longitudinal factor structure of the Brief Psychiatric Rating Scale in schizophrenia.

The focus of this study was the invariance of the factor structure of the Brief Psychiatric Rating Scale (BPRS) over time. An initial sample of 193 individuals diagnosed with nonacute schizophrenia or schizoaffective disorder were administered the BPRS every 6 months over a 3-year period. Multiple-groups confirmatory factor analysis was used to fit the 4-factor oblique model of Mueser, Curran, and McHugo (1997) to both the 16-item and 18-item version of the BPRS. The results show that the model was configurally invariant over time, but it was more invariant for the 16-item version. The findings suggest that the factors, Thought Disturbance, Anergia, Affect, and Disorganized, as measured by the BPRS are distinct symptom constructs that endure over at least a 3-year period, but the strength of their interrelationships varies. Implications for interpretation of change in observed scores over time are discussed.