BD prevalence in depression varies according to diagnostic method

By Mark Cowen, Senior medwireNews Reporter

The prevalence of bipolar disorder (BD) in patients with a major depressive episode (MDE) varies widely depending on the diagnostic method used, researchers report.

T Bschor (Schlosspark-Clinic, Berlin, Germany) and colleagues found that, depending on the diagnostic approach used, between 11.6% and 58.7% of patients with MDE meet criteria for BD.

"It will not be possible to establish a 'true' value for bipolar disorders [in MDE patients] as long as all diagnostic concepts rely on criteria similar to those examined here," comment the researchers in the Journal of Affective Disorders.

The findings come from a study of 252 patients, aged at least 18 years, with an acute MDE who participated in the BRIDGE (Bipolar Disorder: Improving Diagnosis Guidance and Education) study.

All of the participants were assessed for BD using five diagnostic approaches: strict DSM-IV criteria for manic or hypomanic episodes; modified DSM-IV criteria for manic or hypomanic episodes without the exclusion of "induced by substances/antidepressants;" the Bipolarity Specifier Algorithm (BSA), which expands the DSM-IV criteria; the self-assessment Hypomania-Checklist (HCL)-32R; and criteria-free physician's diagnosis based on knowledge and experience.

The team found that the prevalence of BD was lowest when assessed using strict DSM-IV criteria for manic or hypomanic episodes, at 11.6%, and highest when assessed using the HCL-32R, at 58.7%.

Furthermore, 18.4% of the participants had BD according to criteria-free physician's diagnosis, 24.8% when assessed using the modified DSM-IV criteria, and 40.6% according to the Bipolarity Specifier Algorithm.

The researchers note that there was only partial overlap in diagnosis rates among the various diagnostic approaches.

For example, of the 29 patients who met strict DSM-IV criteria for BD, just 17 had the disorder according to physician's diagnosis, despite the latter method classifying more patients as having BD compared with the former.

Bschor et al conclude: "The diagnosis of BD in patients with MDE depends strongly on the method and criteria employed."

They add: "The considerable difference between criteria-free physician's diagnosis and the remaining algorithms indicate the usefulness of criteria lists within the everyday clinical setting."

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