Bipolar spectrum disorders often go unrecognised and undiagnosed. One of the underlying reasons is the poor recognition of bipolar disorder among patients presenting depressive episodes. Our goal was to estimate the 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 psychiatric diagnosis.

971 consecutively outpatients with a current DSM-IV TR diagnosis of major depressive episode were included. Study measures included socio-demographic and clinical data, Clinical Global Impressions–Severity of Illness Scale (CGI-S), Hamilton Depression Scale (HAMD) and MDQ.

905 patients fulfilled criteria to be included in the analysis. All suffered a current depressive episode. 74.3% (n= 671) of the patients had received previously 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.

MDQ showed a positive screen rate for bipolar disorder in 24% of patients with a previous diagnosis of unipolar disorder and a current depressive episode. Screening tools like MDQ could contribute to increased detection of bipolar disorder in patients with depression. Early diagnosis of bipolar disorder may have, therefore, important clinical and therapeutic implications in order to improve the illness course and the long-term functional prognosis.