Psychometric evaluation of the German version of the Yale-Brown Obsessive- Compulsive Scale Modified for Body Dysmorphic Disorder (BDD-YBOCS)

The Yale-Brown Obsessive-Compulsive Scale Modified for Body Dysmorphic Disorder (BDD-YBOCS) is a clinician-administered interview to assess symptom severity in individuals with a BDD diagnosis. It has been translated into German and disseminated into research and practice. However, the psychometric properties of the German version have not been thoroughly evaluated. Therefore, we investigated its psychometric properties, factor structure and provided normative data. Our study included a large pooled sample comprising 350 outpatients with a BDD diagnosis (mean age = 30.35 years, SD = 10.15; gender: 70.6% female, 28.9% male, 0.6% unspecified). Psychometric data supported a good internal consistency of the BDD-YBOCS total score (α = 0.81, ω = 0.86) and an excellent interrater-reliability (ICC = 0.96). The BDD-YBOCS correlated moderately with other measures of BDD symptom severity. Confirmatory factor analysis favored a two-factor structure representing obsessions versus compulsions over a one-factor structure, with the quality of the proposed two-factor structure still being poor. Normative data indicated that BDD-YBOCS scores between 21 and 34 can be considered as typical range in an outpatient sample with a wide range of BDD symptom severity. In conclusion, the German BDD-YBOCS is a brief and psychometrically supported clinician-rated instrument for the measurement of BDD severity.