Comparative evaluation of cut-off criteria of depression severity developed on the basis of classical test theory and Rasch model

Each clinical rating scale used in psychiatry should have evidence-based criteria for assessing the severity of psychopathological constructs measured. The purpose of this study was to conduct the comparative evaluation of the reproducibility and clinical applicability of metric criteria of The Hamilton Rating Scale for Depression (HRSD) developed using the classical test theory (CTT) and developed on the basis of Rasch model. Three samples of research protocols obtained using HRSD included healthy subjects and patients with depression were established for comparative study. As a result of the study, it was found that interpretation criteria developed using the classical test theory had low reproducibility and were not applicable for clinical data. Unlike CTT-criteria metric criteria developed on the base of Rasch model characterized by a high degree of reproducibility and were effectively consistent with clinical data. These results were explained by the conceptual methodological differences of both psychometric approaches in construction of objective measurement and determination of the standard error of measurement.