Many adults being treated for depression in primary care may have undiagnosed bipolar disorder (BD), suggests a new study
It’s likely, say the researchers, that many of these patients are receiving antidepressant monotherapy.

For people who in fact have undiagnosed bipolar disorder, these drugs may be at best unhelpful and at worst harmful.
BD can be difficult to diagnose and is often misdiagnosed as recurrent major depressive disorder
A total of 576 (18.5%) agreed to participate and completed 2 screening instruments for BD (the Hypomania Checklist [HCL-32] and the Bipolar Spectrum Diagnostic Scale [BSDS]).

A total of 370 of them were invited to take part in a one-on-one comprehensive diagnostic and clinical assessment, 154 agreed, and 29 (18.8%) met Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) (DSM-IV) criteria for BD.

The researchers generated 3 estimates of the percentage of patients in primary care with a diagnosis of unipolar depression that may, in fact, have unrecognized BD.
They assumed that all individuals who dropped out of the study by not completing the questionnaire or being assessed did not have BD.

This seems unlikely and therefore provides an extreme lower bound for the proportion of people with undiagnosed bipolar disorder in this population, the researchers write.
Their least conservative estimate of 21.6% assumes that all individuals who did not drop out would have responded in the same way as those who were assessed.
The researchers’ more conservative midestimate of undiagnosed BP in depressed primary care patients is 9.6%.

Therefore, between 3.3% and 21.6% of primary care patients with depression may have unrecognized BD, Dr. Smith and colleagues note.
“It’s therefore important,” says Dr. Smith, “that the possibility of undiagnosed bipolar disorder is given greater recognition in primary care, and that GPs [general practitioners] are supported in developing strategies to ensure that their patients with depression receive the correct diagnosis.”

The findings also suggest that the HCL-32 and BSDS screening questionnaires when used in primary care settings may have “limited utility” in terms of detecting DSM-IV–defined BD.
The positive predictive values were 50.0% and 32.1%, respectively. However, these instruments may be useful for identifying broader definitions of BD, the researchers say.
They also found that sub threshold features of BD were relatively common in the cohort of depressed primary care patients and were associated with a more morbid course of illness and greater psychosocial and quality-of-life impairments.

These findings have important implications for the classification, assessment, and treatment of large numbers of people with depression managed in both primary and secondary care settings.

Read More:  http://www.medscape.org/viewarticle/738579?src=cmemp