Psychometric properties of the Quick Inventory of Depressive Symptomatology in adolescents

Objective: The clinician-rated (QIDS-C-16) and self-report (QIDS-SR16) versions of the 16-item Quick Inventory of Depressive Symptomatology have been extensively examined in adult populations. This study evaluated both versions of the QIDS and the 17-item Children's Depressive Rating Scale - Revised (CDRS-R) in an adolescent outpatient sample. Method: Both the QIDS-C-16 and QIDS-SR16 were completed for the adolescents. Three different methods were used to complete the QIDS-C-16: (a) adolescents' responses to clinician interviews; (b) parents' responses to clinician interview; and (c) a composite score using the most pathological response from the two interviews. Both classical and item response theory methods were used. Factor analyses evaluated the dimensionality of each scale. Results: The sample included 140 adolescent outpatients. All versions of the QIDS, save the parent interview, and the CDRS-R were very reliable (alpha >= 0.8). All four versions of the QIDS are reasonably effective and unidimensional. The CDRS-R was clearly at least two-dimensional. The CDRS-R was the most discriminating among low and extremely high levels of depression. The QIDS-SR16 was the most discriminating at moderate levels of depression. There was no relation between the QIDS scores and concurrent Axis III comorbidities. Conclusion: The QIDS-C-16 and the QIDS-SR16 are suitable for use in adolescents. Copyright (C) 2010 John Wiley & Sons, Ltd.