Validation of the Overall Depression Severity and Impairment Scale (ODSIS) in the Czech Republic

Objectives. The Overall Depression Severity and Impairment Scale (ODSIS) is a brief self-report transdiagnostic measure designed to assess severity and functional impairment associated with depression. Its broader focus makes the measure useful for screening as well as routine outcome monitoring and assessment of overall impact of treatment. The measure is widely used and well applicable in both clinical settings and research context. This study was designed to evaluate the psychometric properties of the Czech version of ODSIS. Statistical analysis. Ordinal Confirmatory Factor Analysis (CFA) was conducted to explore dimensionality. We also examined the ODSIS items using Item Response Theory (IRT). Moreover, internal consistency, test-retest reliability and construct validity were tested. Finally, the cut-off scores for the Reliable Change Index (RCI) and the Clinically Significant Change Index (CSI) were calculated. Sample and setting. The present study assessed selected psychometric properties of the Czech version of the ODSIS in three separate samples: a large general representative sample (n=1738), a clinical sample (outpatients and inpatients; n=58) and a separate online retest sample (n=30). In addition to the ODSIS, participants were asked to respond to conventional measures of depression, anxiety, personality traits, selfesteem, life satisfaction and other scales to determine convergent and divergent validity. Results. Higher depression was observed in females, in widows and widowers, retirees and students. Confirmatory factor analysis indicated an excellent fit of the modified unidimensional model with correlated errors between item 1 and 2: x2(4) = 8.33; p