Objective: Bipolar spectrum disorders often go unrecognised and undiagnosed or misdiagnosed. One of the underlying reasons is the poor recognition of bipolar disorder among patients presenting depressive episodes. The specific aim of this study was to estimate the Mood Disorder Questionnaire (MDQ) rate of positive screens for bipolar disorder in a Spanish sample of outpatients with a current major depressive episode and compare it with their current psychiatric diagnosis. The study was designed to address this specific question.
Method: 971 consecutively outpatients with a current DSM-IV TR diagnosis of a major depressive episode entered this cross-sectional study. Study measures included sociodemographic and clinical data, Clinical Global Impression of Severity of Illness Scale (CGI-S), Hamilton Depression Scale (HAMD) and MDQ.
Results: 905 patients fulfilled criteria to be included in the analysis. All of them presented with a current major depressive episode. 74.3% (n=671) of the patients had received a diagnosis of unipolar depression and 25.7% (n=232) of bipolar disorder by a psychiatrist. Using a MDQ of 7-or-more-item threshold, the global positive screen rate for bipolar disorder was 41.3% (n=373). From the 671 patients with previous unipolar depression diagnosis, 161 (24%) screened positive for bipolar disorder with MDQ, whereas in 232 patients diagnosed of bipolar disorder, 212 (91.4%) screened positive for bipolar disorder.
Conclusions: The MDQ showed a positive screen rate for bipolar disorder in 24% of patients with a previous diagnosis of unipolar disorder and a current major depressive episode. Screening tools like MDQ could contribute to increase detection of bipolar disorder in patients with depression. Early diagnosis of bipolar disorder may have important clinical and therapeutic implications in order to improve the illness course and the long-term functional outcome.