New subscales for an anchored version of the Brief Psychiatric Rating Scale: construction, reliability, and validity in acute psychiatric admissions.

Attending psychiatrists completed an anchored version of the 18-item Brief Psychiatric Rating Scale (BPRS-A) based on admission and evaluation information on a total of 2,921 adult patients treated at 1 public sector acute psychiatric teaching hospital. Exploratory factor analysis was applied to a 6-month sample to construct 4 nonoverlapping subscales: Resistance, Positive Symptoms, Negative Symptoms, and Psychological Discomfort. Confirmatory factor analysis compared these new subscales to 3 other published subscale models using a second 6-month sample. Internal consistency, rater influence, and interrater agreement were estimated in separate studies. Discriminant validity was explored by comparison of diagnosis-based samples. Application of the BPRS-A as a debriefing instrument in the study of symptomatic change and the multiple challenges inherent in psychometric study of such a rating scale in realistic hospital practice are discussed.