Characteristics of bipolar disorder in an Australian specialist outpatient clinic: comparison across large datasets

Objectives: There have been relatively few detailed reports on the sociodemographic and clinical characteristics of bipolar disorder in large outpatient clinical samples. This paper reports on findings from the Black Dog Institute Bipolar Disorders Clinic (BDI-BDC) and compares this dataset with the predominantly outpatient Stanley Foundation Bipolar Disorders Network (SFBN) and Systematic Treatment Enhancement Program for Bipolar Disorder (STEP-BD) samples. Methods: A total of 217 patients with DSM-IV bipolar disorder were assessed in detail in the BDI-BDC using a series of standardized and non-standardized structured interviews. Ninety per cent had bipolar I disorder, and 10% bipolar II disorder. This sample was compared with the SFBN and STEP-BD datasets. Results: The sociodemographic characteristics of the three samples were remarkably similar. Female gender and younger age were overrepresented compared to the general population. Functional impairment, indicated by marital status and labour force participation, was clearly more common among the study subjects than in the general population. In all three samples, prior educational attainment was higher than the general population. With respect to clinical features, approximately half of each sample was euthymic and approximately one-third was in a DSM-IV episode of depression at study entry. One-half reported depression as their first episode of mood disturbance. Similar proportions identified positive family histories of bipolar disorder (40%) and unipolar depression (55%). Other clinical characteristics demonstrated more variation between the samples. The STEP-BD population reported an earlier age of onset. The SFBN subjects reported higher numbers of overall episodes, but psychotic features and suicide attempts were less common than in the BDI-BDC sample. Conclusions: This report highlights the marked commonalities of the sociodemographic and clinical characteristics of patients with bipolar disorder recruited predominantly in the outpatient setting in three different continents, that is, Australia, North America and Europe. It also demonstrates some critical distinctions between such samples, emphasizing the need to be aware of these differences when interpreting findings, such as treatment outcome, from different bipolar disorder datasets.