Screening for bipolar disorder with the Mood Disorders Questionnaire in patients diagnosed as major depressive disorder - the experience in China

Background: Bipolar disorder (BD) is often misdiagnosed as a major depressive disorder (MDD). This study aimed to test the usefulness of the screening tool, the Mood Disorders Questionnaire (MDQ), to identify BD patients misdiagnosed as MDD in Chinese clinical settings.

Methods: A total of 1487 patients treated for MDD were consecutively examined in 13 mental health centers in China. The patients' socio-demographic and clinical characteristics were recorded using a standardized protocol and data collection procedure. The MDQ was completed by patients to identify symptoms characteristic of BD. DSM-IV diagnoses were established using the Mini International Neuropsychiatric Interview (MINI).

Results: Three hundred-nine of the 1487 patients (20.8%) satisfied DSM-IV criteria for BD; 118 (7.9%) for BD-I and 191 (12.8%) for BD-II on the MINI. The optimal cut-off point on the MDQ to differentiate BD from MDD was 3, while cut-off points of 5 and 3 differentiated BD-I and BD-II from MDD, respectively. The maximum sensitivity was 0.31, 0.45 and 0.22 for differentiating BD, BD-I and BD-II from MDD, respectively.

Conclusions: The optimal cutoff points of the MDQ for screening BD in Chinese patients originally diagnosed as MDD were considerably lower than those in earlier studies. The routine clinical use of the MDQ as a screening scale for BD in Chinese patients treated for MDD does not seem to be justified.