Bipolarity Questionnaire: Preliminary Construction of a Screening Questionnaire for Bipolar Disorder

Background Bipolar disorder (BD) is often underdiagnosed or misdiagnosed due to limitations in current diagnostic tools, which may not adequately capture the disorder’s defining characteristics, such as symptom polarity and instability. Existing self-report scales, like the MDQ and HCL-32, have limited sensitivity and are not culturally tailored to Chinese populations. To address this gap, a new self-report questionnaire was developed to aid in the differentiation between unipolar and bipolar depression, with an emphasis on broader symptom coverage. Methods A 21-item self-rated questionnaire was drafted and administered to 445 patients with Major Depressive Disorder (MDD) or Bipolar Disorder (BD) confirmed by structural diagnostical interview according to DSM-5 and a at least 6-month follow-up. The internal consistency was assessed using Cronbach's alpha, structural validity was evaluated through confirmatory factor analysis, and the screening performance was determined using an ROC curve analysis. Results The Cronbach's coefficient for the entire questionnaire was 0.872. Exploratory factor analysis revealed four factors with a cumulative variance contribution of 46.22%. The questionnaire demonstrated good sensitivity (0.66-0.84) and specificity (0.58-0.71) for different BD subtypes, with AUC values ranging from 0.689 to 0.741. Conclusion The Bipolarity Questionnaire is a reliable and valid tool for differentiating unipolar and bipolar depression, with a broader symptom assessment compared to existing tools.