Biopolar disorder screening uncovers hidden anxiety

By Ingrid Grasmo, medwireNews Reporter

Patients who receive a false-positive diagnosis during screening tests for bipolar disorder are likely to have an undiagnosed anxiety disorder, suggest findings published in the Journal of Affective Disorders.

Given the potential clinical impact misdiagnosis can have on the patient population, the finding should "be conceded in the development and refinement of such screening measures and in clinical assessment of the possibility of a bipolar disorder," say Gordon Parker (University of New South Wales, Sydney, Australia) and colleagues.

They add: "If further research confirms the confounding effect of anxiety conditions on false positive diagnoses on bipolar screening measures, this should encourage deletion of items most susceptible to such effects and ideally improve diagnostic accuracy of the screening measures."

In all, 1534 patients attending the Black Dog Institute Depression Clinic completed the Mood Swings Questionnaire (MSQ)-46 and 852 also completed the Mood Disorders Questionnaire (MDQ). The agreement rates with clinical assessment for discriminating bipolar from unipolar depression were 84% for the MSQ-46 and 74% for the MDQ.

Clinical assessment identified 57 and 66 false-positives for the MSQ-46 and MDQ, respectively. The two most common clinical diagnoses made for this group of false-positive patients were unipolar non-melancholic depression (37% for MSQ-46 and 46% for MDQ) and primary anxiety with secondary (non-melancholic) depression (19% for MSQ-46 and 15% for MDQ).

Furthermore, 46% of MSQ-assigned false positives and 63% of MDQ-assigned false positives in the unipolar non-melancholic group had comorbid anxiety conditions. This suggests that patients with anxiety conditions are more likely to affirm hypomanic symptoms in bipolar screening measures and are at consequent risk for misdiagnosis.

Indeed, analysis of MSQ-46 data also showed that patients with false-positives diagnosed with a primary or secondary anxiety disorder were most likely to affirm that they had periods of time during which they felt more confident and capable; had lots of ideas, plans and goals; saw things in an exciting light; felt creative; talked more; had racing thoughts; had heightened senses and emotions; were impatient with people; and were extremely energetic.

However, very few unipolar melancholic patients had sufficient hypomanic symptoms to be falsely assigned as having a bipolar condition, making these key symptoms to consider when making a definitive clinical assessment, says the team.

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