Plumbing the depths: Some problems in quantifying depression severity

We first report further studies of the psychometric properties of the AUSSI), a brief (11-item) self-report depression measure assessing mood state severity and disability in a sample of 270 subjects. Total scores (combining mood stare and disability) correlated well with another self-report measure of depression severity, the Beck, but minimally with both Hamilton and DSM-III-R Global Assessment of Function (GAF) scores. For a sub-sample where we had complete data sets (including a corroborative witness [CW] form of the AUSSI), we established moderate levels of agreement between self-report and CW AUSSI scores, important in supporting the validity of its disability sub-scale. Against expectation, neither mood nor disability AUSSI scale scores differed across clinically meaningful depressive sub-types, while differentiation was demonstrated for the Hamilton and GAF measures, Differentiation for the Hamilton measure was clearly driven by several type-specific component clinical features, but also presumably contributed to by the clinician-rater format. Our study raises questions about the varying reference bases and semantics used by patients, corroborative witnesses and clinicians in rating depression severity, and which may generate similar or contrasting severity estimates across varying depressive sub-types. (C) 1997 Elsevier Science B.V.