To evaluate the extent of hypomanic symptoms in patients presenting with a current major depressive episode (MDE) and to identify characteristics differentiating patients with hypomanic symptoms from those with pure unipolar depression, using the HCL-32 self-assessment tool.

This cross-sectional diagnostic study was performed in eighteen countries. Community- and hospital- based psychiatrists included consecutively all consulting adult patients with a diagnosis of MDE and completed a questionnaire on sociodemographic variables, diagnosis, medical history, treatment and comorbid psychiatric disorders. Each patient completed the Hypomania Self-Rating Scale (HCL-32 R2), and those scoring ≥14 were assigned a diagnosis of bipolar disorder. The frequency of study variables in the bipolar disorder (BD) and unipolar depression subgroups were compared.

A total of 5635 patients were included. Overall, 1645(39%) had received a diagnosis of BD, 703(16%) fulfilled DSM-IV-TR criteria for BD and 2942(54%) scored ≥14 on the HCL-32. Patients scoring ≥14 on the HCL-32 were significantly more likely to have experienced a mood switch in response to antidepressants (OR:3.4), a family history of bipolarity (OR:2.4), comorbid substance abuse (OR:2.1) or borderline personality disorder (OR:1.7) and current mixed-state symptoms (OR:1.5).

In patients with DSM-IV MDE self-assessed, hypomanic symptoms were present in 54% of patients, whereas only 16% fulfilled DSM-IV criteria for bipolar disorder. However, these patients presented features recognised to be associated with bipolar disorder. The presence of bipolarity in patients presenting with a major depressive disorder may be frequent and use of this questionnaire would contribute to improve awareness and prompt better diagnosis.