Background
Although delusions are the hallmark of major depression with psychotic features, a
scale to measure the intensity of beliefs across multiple delusional domains in this
condition has been unavailable. The development and assessment of the Delusional Assessment
Scale (DAS) are described.
Methods
Scale items were selected initially based on previous studies of delusional ideation
in schizophrenia. A three-point item to assess mood congruence was added. A 15-item
scale was assessed in 92 subjects participating in the four-site collaborative study
of the pharmacotherapy of major depression with psychotic features. Maximum likelihood
method was used to determine scale factors. The internal consistency of these factors
was determined. Comparisons between scale scores and ratings from the Brief Psychiatric
Rating Scale (BPRS) (Overall and Gorham 1962) were used to assess convergent and discriminant
validity.
Results
The data were fit by a five-factors model (impact, conviction, disorganization, bizarreness,
and extension). Inter-rater reliability of the five factors ranged from .77 for conviction
and .74 for impact to .37 for disorganization. Internal consistency for each of the
five factors was ≥.72. Scores on specific domains were significantly correlated with
the BPRS unusual thought content item and positive symptom subscale scores.
Conclusions
The DAS is a reliable measure of 5 delusional domains.
Key Words
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Article info
Publication history
Published online: October 17, 2006
Accepted:
May 23,
2006
Received in revised form:
May 23,
2006
Received:
November 28,
2005
Identification
Copyright
© 2006 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.
