Consistency of Brief Psychiatric Rating Scale factor structure across a broad spectrum of schizophrenia patients.

BACKGROUND: The Brief Psychiatric Rating Scale (BPRS) has been the workhorse of psychopathology assessment in studies of schizophrenia and related psychotic disorders for over 40 years. Our goal was to evaluate the discriminant validity of the BPRS across the broad spectrum of persons with schizophrenia. SAMPLING AND METHODS: The total sample of 565 subjects with schizophrenia (84%) or schizoaffective disorder (16%) came from eight separate studies conducted under the aegis of the UCLA Clinical Research Center for Schizophrenia and Psychiatric Rehabilitation over a period of 15 years. The total sample could be divided into three subsamples based on illness chronicity and degree of refractoriness to treatment: Recent-onset patients had been ill for less than 2 years (n = 178), stable chronic patients between 2 and 19 years (n = 243) and treatment-refractory patients for more than 19 years (n = 144). Exploratory principal components analysis and varimax rotation were performed on the total sample. The results of each of the three subsamples were compared to the total sample using a correlation matrix and by calculating a coefficient of congruence.
RESULTS: A 4-factor solution was considered the most interpretable for each subsample, reflecting the same 4 components identified in the total sample: positive symptoms, negative symptoms, agitation-mania and depression-anxiety. Correlation coefficients and coefficient of congruence were very high, ranging from 0.91 to 0.98.
CONCLUSIONS: The consistency of the 4-factor solution of the 24-item BPRS across the range of subjects, from first psychotic episode to long-stay, institutionalized patients, supports the use of these factors and this instrument as a whole to track changes over time and with treatment in research and clinical samples. (c) 2007 S. Karger AG, Basel.