Improving Depressive Symptom Measurement in Adolescents: A Psychometric Evaluation of the Quick Inventory of Depressive Symptomatology, Adolescent Verison
Haley, Charlotte Louise
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Major depressive disorder (MDD) in children and adolescents is a common and debilitating psychiatric disorder. Current instruments used to identify the presence of and monitor the treatment of depression in adolescents vary in validity, reliability, appropriateness, cost and ease of administration, such that there is not yet an established instrument that meets all the needs of clinicians working with adolescents. The 16-item Quick Inventory of Depressive Symptomatology (QIDS16), developed and successfully validated as an accurate, brief and economical measure of depressive symptom severity in adults, has been modified to an adolescent version (QIDS-A17). Results from recent studies suggest that the QIDS-A17 may meet the need for a freely available, easy to administer, psychometrically-sound measure of core depressive symptoms for adolescents that can be used both as a screening tool and as a measure of symptom severity in both research studies and clinical practice. The current study aims to validate the QIDS-A17 instruments, including the self-report format (QIDS-A-SR), and two clinician-rated formats (QIDS-A-C[Adolescent] and QIDS-A-C[Composite]) in an adolescent outpatient population. The study included 103 outpatient adolescents ranging from 8 to 17 years of age. During a single visit, adolescents completed the QIDS-A-SR. A clinician completed the clinician-rated versions separately for adolescents (QIDS-A-C[Adolescent]) and parents (QIDS-A-C[Composite]) and the Children's Depression Rating Scale-Revised (CDRS-R). Classical Test Theory (CTT) analysis found all three QIDS-A17 measures to show strong internal consistency and correlate significantly to the CDRS-R, although the CDRS-R was the most reliable. Factor and parallel analysis found all four measures to be unidimensional. Item Response Theory (IRT) analysis found results that complemented the reliability results found in CTT. All four measures demonstrated diagnostic validity based on univariate and multivariate logistic regression, ANOVA, and MANOVA analyses. Scores on all four measures were equated to create conversion tables to facilitate translation of scores between tests. Although the three clinician-rated measures (CDRS-R, QIDS-A-C[Adolescent], QIDS-A-C[Composite]) were slightly more reliable than the QIDS-A-SR, the QIDS-A-SR demonstrated satisfactory reliability, validity, and discriminate utility such that it can be used effectively in settings that would benefit from a quick, valid, freely available self-report measure of depression in adolescents.