Validity of the Chinese version Mood Disorder Questionnaire (MDQ) and the optimal cutoff screening bipolar disorders

To investigate the validity of the Chinese version of Mood Disorder Questionnaire (C-MDQ) in China. Patients with bipolar disorders (BP, N=284) and patients with unipolar depressive disorder (UP, N=134) were assessed with the C-MDQ. The Eigenvalues of the first two factors were 3.15 and 2.09, respectively. The Cronbach's alpha of the C-MDQ was 0.79. The frequency of positive responses of UP patients was significantly lower than those of BP patients for 12 items except the seventh item. A C-MDQ screening score of seven or more was the best cutoff between BP and UP. The C-MDQ could distinguish between bipolar II disorder (BP-II) and UP, and the best cutoff was five. A cutoff of five had a sensitivity of 0.80 and a specificity of 0.54 between BP and UP. This study demonstrated the good validity of C-MDQ in China. The best cutoff between BP-II and UP can be regarded as the optimal cutoff between BP and UP to improve the sensitivity of screening for BP-II. Five should be the optimal cutoff between the BP and UP when only the 13 items of the questionnaire are used in China.