Standardization of the Teate Depression Inventory: Preliminary results

STANDARDIZATION OF THE TEATE DEPRESSION INVENTORY:PRELIMINARY RESULTS Balsamo, Michela & Saggino, Aristide Department of Biomedical Sciences, “G. d’Annunzio” University, Chieti-Pescara, Italy Introduction: On the basis of diagnostic criteria for Major Depression Episode of DSM-IV-TR (2000), we have constructed an Italian 21-item unidimensional self-report scale of depression, named TDI (Balsamo, 2006), using item-response theory, specifically a modified version of the Rasch one-parameter modelling (Rasch, 1960-1980), proposed by Andrich (1988). Aims and Method: Our aim was to provide a contribution to standardization of the TDI. The sample consists of about 700 Italian outpatients with various psychiatric diagnosis. A sample of about 700 Italian healthy subjects, prevalently undergraduate students, was also administered the TDI to serve as a comparative normal group. Results: We have calculated correlations between TDI total score and age and sex of subjects. An estimate of the stability of the TDI over time was based on the responses of a subsample of 30 Italian outpatients who were administered the TDI at the times of their first and second therapy sessions, approximately 1 week apart. The test-retest correlation was significant. To estimate the convergent and discriminant validity of the TDI, we administered the Beck Depression Inventory-II (BDI-II; Beck, Steer e Brown, 1996) and the State-Trait Anxiety Inventory (STAI; Spielberger, 1991). Evidence of the TDI factorial validity is provided by the intercorrelations among the 21 TDI items, which were first calculated from the responses of the sample of psychiatric outpatients and then of the student sample. Discussion and Conclusions: The TDI is a 21-item unidimensional self-report scale of depression selected by Rasch analysis, which seems to catch the nucleus of depressive symptomatology. It has some advantages, as: 1) ordered sequence of the thresholds of each of 21 items; 2) good discriminative ability between normal and clinical subjects; 3) good reliability and convergent and discriminant validity Thus, it could be a valid screening instrument in that it sensitively discriminates between outpatients and normals.