Validity and reliability of the Brief version of Quality of Life in Bipolar Disorder” (Bref QoL.BD) among Chinese bipolar patients

Abstract

BackgroundPrevious literatures on quality of life (QoL) in bipolar disorder (BD) strongly suggested that a disease-specific QoL measure for patients with BD should be developed to evaluate QoL more specifically and reliably. To our knowledge, “Quality of Life in Bipolar Disorder” (QoL.BD) is the first and only questionnaire produced to specifically measure QoL in people with BD. In China, there is no disease-targeted measure available to specifically measure QoL in Chinese patients with BD. ObjectiveThe aim of the study is to revise and validate the brief version of the QoL.BD (Bref QoL.BD ) into Chinese version. MethodsAll the items of the Bref QoL.BD was translated into Chinese language, using the Brislin translation mode. The questionnaire was administered to a total sample of 231 subjects, including 101 BD patients and 130 healthy controls, to test the psychometric properties of Bref QoL.BD (e.g. internal consistency, retest reliability, content validity, item analysis, confirmatory factor analysis, criterion validity, convergent validity, discriminative validity and feasibility). ResultsThe Chinese version of the Bref QoL.BD had very high internal consistency (Cronbach’s alpha=0.815) and retest reliability (intraclass correlation coefficient (ICC )=0.808). Confirmatory factor analysis (CFA) validated the original one-factor structure. The direction and magnitude of correlations with 36-item Short-Form Health Survey (SF-36; rs= 0.313, P<0.001) and 17-Hamilton Depression Rating Scale(HAMD; rs=−0.328, P <0.001) suggesting the criterion validity and convergent validity, respectively. The scores of Bref QoL.BD in subsyndromic BD group (HDRS≥4 and BRMS≥3), asymptomatic BD group (HDRS≤3 and BRMS≤2) and the control group significantly decreased successively, suggesting a discriminative validity of the instrument. LimitationsCross-sectional design and a small sample size from only one tertiary care center. And BD patients enrolled were euthymic, excluding the acute BD patients. ConclusionsThe Chinese version of the Bref QoL.BD is a feasible, reliable and valid tool for the assessment of QoL for Chinese BD patients.