Objective: The authors developed and evaluated the reliability and validity of the Brown Assessment of Beliefs Scale, a clinician-administered seven-item scale designed to assess delusions across a wide range of psychiatric disorders.
Method: The authors developed the scale after reviewing the literature on the assessment of delusions. Four raters administered the scale to 20 patients with obsessive-compulsive disorder (OCD), 20 patients with body dysmorphic disorder, and 10 patients with mood disorder with psychotic features. Audiotaped interviews of scale administration conducted by one rater were independently scored by the other raters to evaluate interrater reliability. The scale was administered to 27 patients twice to determine test-retest reliability. Other insight instruments as well as scales that assess symptom severity were administered to assess convergent and discriminant validity. Sensitivity to change was assessed in a multicenter treatment study of sertraline for OCD.
Results: Interrater and test-retest reliability for the total score and individual item scores was excellent, with a high degree of internal consistency. One factor was obtained that accounted for 56% of the variance. Scores on the Brown Assessment of Beliefs Scale were not correlated with symptom severity but were correlated with other measures of insight. The scale was sensitive to change in insight in OCD but was not identical to improvement in severity.
Conclusions: The Brown Assessment of Beliefs Scale is a reliable and valid instrument for assessing delusionality in a number of psychiatric disorders. This scale may help clarify whether delusional and nondelusional variants of disorders constitute the same disorder as well as whether delusionality affects treatment outcome and prognosis.