The truth continues expanding its horizons and the fallacies are falling:
Bipolar Disorder Often Mistaken for Depression in Primary Care
News Author: Megan Brooks
CME Author: Désirée Lie, MD, MSEd March 8, 2011
Désirée Lie, MD, MSED
As
many as 20% of adults being treated for depression in primary care may
have undiagnosed bipolar disorder (BD), suggests a new study from the
United Kingdom published online February 3 in the British Journal of
Psychiatry.
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," lead researcher Daniel J. Smith, MD, MRCPsych, of the
Department of Psychological Medicine and Neurology, Cardiff University
School of Medicine and University Hospital of Wales, cautions in a
statement.
BD
can be difficult to diagnose and is often misdiagnosed as recurrent
major depressive disorder, Dr. Smith and colleagues point out in their
report. They invited 3117 adults from South Wales who were being treated
for depression by their primary care physician to participate in their
study.
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 who may, in fact,
have unrecognized BD.
Their
most conservative estimate of 3.3% is based on the strictest assumption
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.
In
line with other studies, they also found that subthreshold 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," they conclude.
The
study was funded by an MRC/Welsh Assembly Government Partnership Award.
Dr. Smith is funded by a Postdoctoral Fellowship from the National
Institute of Health Research. Dr. Smith discloses having received
honoraria for speaking at educational meetings organized by AstraZeneca
and Lilly.
Br J Psychiatry. Published online February 3, 2011.
Related Link
The
Mayo Clinic’s Web page on bipolar disorder provides in-depth
information for patients about the disease, its diagnosis, and
management and provides links to other resources for patients.
Clinical Context
BD
is often under-recognized in clinical practice and is often
misdiagnosed as recurrent major depressive disorder. The mean delay for
the diagnosis of BD is estimated as 10 years from onset of the first
symptoms. There may be a high prevalence of undiagnosed BD among
patients with unipolar depression, and the HCL-32 and BSDS may be useful
for screening for manic symptoms in a primary care population.
This
2-phase screening study was conducted in primary care to determine the
prevalence of BD among patients with unipolar depression and the
usefulness of the 2 screening instruments to diagnose manic symptoms.
Study Highlights
-
Included were patients with a current diagnosis of unipolar depression from 11 of 45 primary care practices in a
single health board in South Wales. These patients had detailed
diagnostic, clinical, psychosocial, and quality-of-life data.
- Participants were invited to complete the HCL-32 and BSDS questionnaires.
- 576
participants completed the questionnaires and were divided into 2
groups: high scorers (≥ 14 on the HCL-32 or ≥ 13 on the BSDS; n = 411)
and low scorers (< 14 on the HCL-32 or < 13 on the BSDS; n = 165).
- All of the low scorers and half of the high scorers participated in a comprehensive diagnostic and clinical assessment.
- The
assessments included the Mini International Neuropsychiatric Interview
and a structured assessment of psychosocial and medical history and
medications.
- A 2-phase sampling technique was used to estimate the prevalence of BD among the patients.
- The investigators assessed the usefulness of the HCL-32 and BSDS with receiver operating characteristic curves.
- 116
of 154 participants interviewed had a history of DSM-IV–defined major
depressive disorder, and 29 (18.8%) satisfied DSM-IV criteria for BD.
- With
the 2-phase sampling technique, the estimate of the prevalence of BD
among those with unipolar depression ranged from 3.3% to 21.6%, with a
midpoint estimate of 9.6%.
- Both
the HCL-32 and the BSDS could distinguish between BD and major
depressive disorder with reasonable precision (area under the curve was
0.81 for the HCL-32 and 0.71 for the BSDS).
- The
optimal cutoff values were a score of 18 or higher on the HCL-32 and a
score of 12 or higher for the BSDS, but the positive predictive value
was low (50% for the HCL-32 and 32.1% for the BSDS).
- In
the sample of 116 participants, 60 had major depressive disorder with
manic symptoms, and 56 had major depressive disorder only.
- Patients
with major depressive disorder accompanied by manic symptoms were
younger, had a younger age of onset of depression, reported more
frequent symptoms of depression, and were more likely to have comorbid
alcohol dependence.
- They also had greater difficulty with functioning and relationships and had lower quality-of-life scores.
- Overall,
patients with major depressive disorder and manic symptoms had more
severe depression, poorer psychosocial functioning, and worse quality of
life vs patients with major depressive disorder only or those with no
subthreshold manic symptoms.
- The
authors concluded that the prevalence of BD among patients with
unipolar depression ranged from 3.3% to 21.6%, and up to 1 in 30
patients in primary care with unipolar depression may have unrecognized
BD.
- They also noted that both the HCL-32 and SDS had a low positive predictive value for diagnosing DSM-IV–defined BD.
Clinical Implications
