Measurement invariance and psychometric analysis of Kutcher Adolescent Depression Scale across gender and marital status

Background: The Kutcher Adolescent Depression Scale (KADS) has been studied across Canada and some other countries during the past almost 15 years. The scale is a self-report tool to diagnose and monitor clinical depression in adolescents. A brief review of previous studies on KADS showed the lack of evaluation of KADS fairness/equivalence in measuring depression among identified groups. Methods: To examine the psychometric properties and measurement invariance of the KADS, responses of 407 participants were analyzed using item response theory (IRT) and ordinal logistic regression (OLR). Relevant measures of effect size were utilized to interpret the results. Results: Findings of the parallel factor analysis confirmed unidimensionality of the KADS and the partial credit IRT model found to be the best fitting model for analyzing the scale. OLR analysis detected three items across gender and one item across marital status to function differentially. An assessment of effect sizes implied negligible differences for practical considerations. Limitations: A note of caution is necessary with respect to interpreting results of measurement invariance across Gender. The sample analyzed in this study was predominantly female and this might have affected our findings. A similar analysis with a more balanced sample is recommended. Conclusions: This study was a significant step towards providing theoretical and practical information regarding the assessment of depression among adolescents by presenting adequate evidence regarding the psychometric properties of KADS-11. Future studies may look at different methods for assessing invariance and different groups for strengthening conclusions with respect to the KADS.