Validation of the behavioural activity rating scale (BARS)™: a novel measure of activity in agitated patients

Abstract

We report psychometric results of the Behavioural Activity Rating Scale (BARS™) using data from three Phase III clinical trials of intramuscular ziprasidone in acutely agitated patients with psychosis (Studies 1 and 2) or in stable psychotic patients (Study 3). Convergent validity and divergent validity were assessed with baseline data from Studies 1 and 2 in subjects with acute agitation. To investigate convergent validity, we sought Pearson and Spearman correlation of BARS™ scores with scores on the Clinical Global Impression of Severity (CGI-S) Scale and a predefined cluster of agitation-related items from the Positive and Negative Syndrome Scale (PANSS). For divergent validity, we sought Pearson and Spearman correlation between BARS™ scores and a predefined cluster of PANSS items measuring negative symptoms. Discriminant validity was investigated with the help of subjects with moderate psychopathology (Study 3). Wilcoxon rank-sum and two-sample t tests determined whether mean (or median) BARS™ scores differed between subjects with acute agitation (Studies 1 and 2) and moderate psychopathology (Study 3). Responsiveness to treatment effect and rater reliability were also evaluated. In Study 2, Pearson correlation coefficients of BARS™ scores with PANSS agitation items and CGI-S were moderate ( convergent validity) and statistically significant ( P<0.005). The correlation between BARS™ scores and PANSS negative component scores was low ( divergent validity). Treatment effect size was larger for BARS™ than for PANSS agitation items and CGI-S ( responsive to treatment differences). Virtually perfect inter- and intra-rater reliability was achieved. Study 1 produced similar results. BARS™ showed psychometrically valid properties for measurement of behavioral activity in acutely agitated patients with psychosis.