Prevalence and predictors of bipolar disorders in patients with a major depressive episode: The Japanese epidemiological trial with latest measure of bipolar disorder (JET-LMBP)

BackgroundFor patients with a major depressive episode, early differential diagnosis of bipolar disorder and subsequent appropriate treatment are critical. This study, conducted in clinical settings in Japan, examined patients with a major depressive episode to investigate the prevalence and predictors of bipolar disorders.MethodsA total of 448 patients with a major depressive episode were interviewed using the Mini-International Neuropsychiatric Interview to determine the presence of mood episodes and psychiatric comorbidities. The diagnosis of bipolar disorder was based on the collected information according to the DSM-IV-TR.ResultsOf the 448 patients with a major depressive episode, 114 patients (25.4%) were diagnosed with bipolar disorder. Multivariate logistic regression identified five predictors that were significantly correlated with bipolar disorder: antidepressant-related switch to mania/hypomania, mixed depression, two or more previous mood episodes within the past year, early age at the onset of a major depressive episode (<25 years), and a history of suicide attempts. The area under the curve of receiver operating characteristic analysis based on the multivariate logistic regression of the five predictors was 0.849.LimitationsThe diagnosis of bipolar disorder in patients was already conclusively confirmed by long illness observations but was not confirmed by a prospective study.ConclusionsIn patients with a major depressive episode, the differential diagnosis of bipolar disorder and major depressive disorder, which exhibit similar depressive symptoms, is essential. Several predictors identified in the present study may be useful in supporting a differential diagnosis of these disorders in routine clinical practice.