Clinical assessment of bipolar depression: Validity, factor structure and psychometric properties of the Korean version of the Bipolar Depression Rating Scale (BDRS)

Background: The Bipolar Depression Rating Scale (BDRS) is a scale for assessment of the clinical characteristics of bipolar depression. The primary aims of this study were to describe the development of the Korean version of the BDRS (K-BDRS) and to establish more firmly its psychometric properties in terms of reliability and validity. Methods: The study included 141 patients (62 male and 79 female) who had been diagnosed with bipolar disorder, were currently experiencing symptoms of depression, and were interviewed using the K-BDRS. Other measures included the Montgomery and Asberg Depression Scale (MADRS), the 17-item Hamilton Depression Scale (HAMD), and the Young Mania Rating Scale (YMRS). Additionally, the internal consistency, concurrent validity, inter-rater reliability, and test-retest reliability of the K-BDRS were evaluated. Results: The Cronbach's α-coefficient for the K-BDRS was 0.866, the K-BDRS exhibited strong correlations with the HAMD (r=0.788) and MADRS (r=0.877), and the mixed symptoms score of the K-BDRS was significantly correlated with the YMRS (r=0.611). An exploratory factor analysis revealed three factors that corresponded to psychological depressive symptoms, somatic depressive symptoms, and mixed symptoms. Conclusions: The present findings suggest that the K-BDRS has good psychometric properties and is a valid and reliable tool for assessing depressive symptoms in patients with bipolar disorder.