Prevalence and characteristics of undiagnosed bipolar disorders in patients with a major depressive episode: the BRIDGE study.

Context: Major depressive disorder, the most common psychiatric illness, is often chronic and a major cause of disability. Many patients with major depressive episodes who have an underlying but unrecognized bipolar disorder receive pharmacologic treatment with ineffective regimens that do not include mood stabilizers.
Objective: To determine the frequency of bipolar disorder symptoms in patients seeking treatment for a major depressive episode.
Design: Multicenter, multinational, transcultural, cross-sectional, diagnostic study. The study arose from the initiative Bipolar Disorders: Improving Diagnosis, Guidance and Education (BRIDGE).
Setting: Community and hospital psychiatry departments.
Patients: Participants included 5635 adults with an ongoing major depressive episode.
Main Outcome Measures: The frequency of bipolar disorder was determined by applying both DSM-IV-TR criteria and previously described bipolarity specifier criteria. Variables associated with bipolarity were assessed using logistic regression.
Results: A total of 903 patients fulfilled DSM-IV-TR criteria for bipolar disorder (16.0%; 95% confidence interval, 15.1%-17.0%), whereas 2647 (47.0%; 95% confidence interval, 45.7%-48.3%) met the bipolarity specifier criteria. Using both definitions, significant associations (odds ratio > 2; P < .001) with bipolarity were observed for family history of mania/hypomania and multiple past mood episodes. The bipolarity specifier additionally identified significant associations for manic/hypomanic states during antidepressant therapy, current mixed mood symptoms, and comorbid substance use disorder.
Conclusions: The bipolar-specifier criteria in comparison with DSM-IV-TR criteria were valid and identified an additional 31% of patients with major depressive episodes who scored positive on the bipolarity criteria. Family history, illness course, and clinical status, in addition to DSM-IV-TR criteria, may provide useful information for physicians when assessing evidence of bipolarity in patients with major depressive episodes. Such an assessment is recommended before deciding on treatment.