AIM: The psychometric properties of the Brief Psychiatric Rating Scale, the Beck Anxiety Inventory (BAI), and the Beck Depression Inventory (BDI) were tested in a sample of 134 patients with a substance use disorder and a non-substance related psychiatric disorder in a special inpatient dual diagnosis treatment unit.
METHODS: Subjects were assessed at baseline. At discharge on average 6 months post-intake, 78% of patients were re-assessed using the same instruments. All instruments were tested in (1) their ability to discriminate patients with different diagnoses at baseline and follow-up using comparison of area under the curves, and (2) their temporal stability. Moderator regression was used to test whether thought disorder at baseline had any effect on the test-retest rank-order stability of other instruments.
FINDINGS: The BPRS Thought Disorder scale was able to discriminate between patients with and without schizophrenia spectrum diagnoses, and the BDI was able to discriminate between patients with and without mood disorders and schizoaffective disorders at intake to treatment, and each instrument was significantly better than the other at discriminating relevant diagnostic groups. Discriminant correlations between the BDI and the BAI were high and statistically significant. Moderator regression analyses showed no indication that any of the scales were less stable at higher levels of thought disorder.
CONCLUSIONS: It is concluded that dual diagnosis patients can be reliably assessed for symptoms using the BDI and some subscales of the BPRS.