Psychometric properties of the Chinese version of the Bipolar Spectrum Diagnostic Scale

Aim and objectives.: The aim of this study was to test the psychometric properties of the Chinese version of the Bipolar Spectrum Diagnostic Scale (C-BSDS) in a Chinese population to serve as an aid to clinical diagnosis of bipolar disorders. Background.: Bipolar spectrum disorders are often misdiagnosed because of the wide range of symptoms seen in patients. The consequences of delayed diagnoses or misdiagnoses can be devastating. Design.: A cross-sectional research design. Method.: Two hundred patients with affective disorders from a psychiatric outpatient clinic in Taiwan were enrolled. Internal consistency reliability and two-week test-retest reliability were performed to evaluate the reliability of the C-BSDS. Expert content validity and factor analysis were used for testing construct validity. To evaluate sensitivity and specificity, the Chinese version of the Mini International Neuropsychiatric Interview (MINI) was used as the gold standard for diagnosis. Results.: The internal consistency coefficient measured by intra-class correlation (ICC) was 0·81, the test-retest reliability coefficient was 0·85 and the expert validity was 0·85. For construct validity, 'irritable and hyper-energetic factors' and 'depressed and lack of energy factors' were extracted by factor analysis. These two factors reflected the structure of the original scale and accounted for 33·27% of the variance. The optimal cut-off was 12, which yielded a sensitivity of 74 and a specificity of 0·97 for detecting bipolar disorder and for bipolar II disorder these were 0·79 and 0·68, respectively. Conclusions.: The C-BSDS showed good reliability and validity, and the results were consistent with the English version of the BSDS. Therefore, the C-BSDS is an effective tool for evaluation of a Chinese population. Relevance to clinical practice.: The BSDS can further increase the detection rate of bipolar disorders, especially bipolar II disorder, with satisfactory sensitivity and specificity. It can effectively assist with clinical screening of patients for bipolar spectrum disorders.