Psychometric evaluation of the German version of the Beliefs about Depression Questionnaire (BDQ)

Abstract

Background: The objective of this study was to psychometrically evaluate the German version of the Beliefs about Depression Questionnaire (BDQ). This illness specific measure is based on Leventhals five dimensions of illness perceptions (identity, timeline, causes, cure/control, consequences). Methods: Analyses were carried out in a cross-sectional study of N = 198 depressive inpatients. Factorial validity and factor reliability were analysed using confirmatory factor analysis. Measures of depression severity, self-efficacy, and generic illness beliefs were used to investigate construct validity. Test-retest reliability was determined in a sub-sample (N = 47). Findings: The factorial structure of the dimension identity was rejected. The structure of timeline was fully -and the structure of the other dimensions partly- confirmed. Altogether, 14 of the 16 remaining scales show acceptable factor reliability coefficients (.63 - .99) and 15 scales exhibit acceptable test-retest reliability (ICC ≥ .496). BDQ-scales and measures were associated in the expected way. Discussion: The German BDQ is a nearly acceptable reliable and valid measure, which enables depression-specific assessment of patients’ perception in German samples. Nonetheless, potential for improvement remains.