Background: This paper presents the methodology and clinical data in mid-stream from a French multi-center study (EPIDEP) in progress on a national sample of patients with DSM-IV major depressive episode (MDE). The aim of EPIDEP is to show the feasibility of validating the spectrum of soft bipolar disorders by practising clinicians. In this report, we focus on bipolar II (BP-II).
Method: EPIDEP involves training 48 French psychiatrists in 15 sites; construction of a common protocol based on the criteria of DSM-IV and Akiskal (Soft Bipolarity), as well as criteria modified from the work of Angst (Hypomania Checklist), the Ahearn-Carroll Bipolarity Scale, HAM-D and Rosenthal Atypical Depression Scale; Semi-Structured Interview for Evaluation of Affective Temperaments (based on Akiskal-Mallya), self-rated Cyclothymia Scale (Akiskal), family history (Research Diagnostic Criteria); and prospective follow-up.
Results: Results are presented on 250 (of the 537) MDE patients studied thus far during the acute phase. The rate of BP-II disorder which was 22% at initial evaluation, nearly doubled (40%) by systematic evaluation. As expected from the selection of MDE by uniform criteria, inter-group comparison between BP-II vs unipolar showed no differences on the majority of socio-demographic parameters, clinical presentation and global intensity of depression. Despite such uniformity, key characteristics significantly differentiated BP-II from unipolar: younger age at onset of first depression, higher frequency of suicidal thoughts and hypersomnia during index episode, higher scores on Hypomania Checklist and cyclothymic and irritable temperaments, and higher switching rate under current treatment. Eighty-eight percent of cases assigned to cyclothymic temperament by clinicians (with a cut-off of 10/21 items on self-rated cyclothymia) were recognized as BP-II. Evaluation of this temperament by clinician and patient correlated at a highly significant level (r=0.73; p <0.0001). Cyclothymia and hypomania were also correlated significantly (r=0.51; p < 0.001).
Limitation: In a study conducted in diverse clinical settings, it was not possible to assure that clinicians making affective diagnoses were blind to the various temperamental measures. However, bias was minimized by the systematic and/or semi-structured nature of all evaluations.
Conclusion: With a systematic search for hypomania, 40% of major depressive episodes were classified as BP-II, of which only half were known to the clinicians at study entry. Cyclothymic temperamental dysregulation emerged as a robust clinical marker of BP-II disorder. These data indicate that clinicians in diverse practice settings can be trained to recognize soft bipolarity, leading to changes in diagnostic practice at a national level.