Objective: Self-report instruments commonly used to assess depression in adolescents have limited or unknown psychometric properties in this age group. We report the evaluative properties of the Kutcher Adolescent Depression Scale (KADS), a self-report scale designed specifically for identifying depressed adolescents and for monitoring symptom severity over time.
Methods: One hundred and six adolescents with major depression disorder (MDD) enrolled in an 8-week, double-blind, placebo-controlled study of paroxetine. Efficacy assessments were conducted on days 0 (baseline), 7, 14, 21, 28, 42, and 56 using the self-rated KADS and the clinician-rated Children's Depression Rating Scale-Revised (CDRS-R), Clinical Global Impression (CGI) of severity, and Global Assessment of Functioning (GAF) scale. The data were initially examined to establish which of the 16 KADS items showed greatest sensitivity to change. Subsequent analyses then compared the evaluative properties of three versions of the KADS: the full-length KADS, a six-item subscale previously established as a screening tool, and an 11-item subscale optimized for sensitivity to change.
Results: Within-subject correlations among subjects' KADS scores and their clinician-rated scale scores showed that clinician-rated changes in severity were significantly better corroborated by the 11-item KADS (mean correlations with the CDRS-R, CGI, and GAF: r = 0.69, 0.60, and -0.70, respectively) than by the six-item KADS (r = 0.62, 0.56, and -0.63, respectively) and at least as well corroborated as by the full-length KADS (r = 0.64, 0.56, and -0.67, respectively). Furthermore, in terms of mean percentage change in scores from day 0 to day 56, the 11-item KADS (59%) significantly outperformed the full-length KADS (46%) and all three clinician-rated scales (43%, 37%, and 29%, respectively) and at least matched the performance of the six-item KADS (56%).
Conclusions: These results suggest that the 11-item self-rated KADS is a sensitive measure of treatment outcome in adolescents diagnosed with MDD.