by Michael O'Leary
ClinicalPainAdvisor.com
September 29, 2015
September 29, 2015
About one in five patients with fibromyalgia (FM) has comorbid bipolar disorder (BD), according to a new study published in the Journal of Affective Disorders.1
The findings suggest that FM patients be screened for BD before receiving antidepressant therapy that might trigger mania when administered without a mood stabilizer. (published site)
Led by coauthors Paul Kudlow, MD and Joshua Rosenblat, MD,
from the University of Toronto, Canada, the meta-analysis is the first
to quantify the prevalence of BD in FM, and raises concerns about the
common use of antidepressants in this population.
Researchers pooled data from 9 studies that met the
inclusion criteria of incidence or prevalence of BD in the FM sample,
and calculated an odds ratio from the 4 case-control studies using
standard meta-analytic methods.
Results showed that out of 806 patients diagnosed with
fibromyalgia, 175 (21%) also had a diagnosis of bipolar disorder.
Further analysis revealed that FM patients are 7.5 times more likely to
also have bipolar disorder than those without fibromyalgia.
The role of antidepressants in fibromyalgia treatment
Fibromyalgia is a disorder of unknown origin that is characterized by widespread pain, abnormal pain processing,
sleep disturbance, fatigue, and psychological distress. Data from the
Centers for Disease Control and Prevention indicates that the prevalence
of FM is about 2%, affecting an estimated 5 million adults in 2005.1
Three drugs have been approved by the US Food and Drug
Administration (FDA) for the treatment of fibromyalgia: pregabalin, and
the serotonin and norepinephrine reuptake inhibitors (SNRIs), duloxetine
and milnacipran. Selective serotonin reuptake inhibitors (SSRIs), such
as fluoxetine and sertraline, are also often prescribed off-label for
fibromyalgia when mood is a major symptom.2
“The prevalence of pain and depression has been well established,” Dr. Kudlow told ClinicalPainAdvisor.com.
“Antidepressants are first-line treatments for depression and comorbid
chronic pain disorders, such as fibromyalgia. In contrast, there isn't
much in the literature examining the comorbidity of bipolar disorder and
fibromyalgia. To my knowledge, this is the first meta-analysis that has
been done on it.”
Limitations of the study
Dr. Kudlow was quick to add that the findings are limited
by the low number of available studies and the heterogeneity of study
methods and results. The 9 included studies showed a high degree of
variability, with BD prevalence rates ranging from 0% to 70%.
“With just nine heterogeneous studies, it is difficult to
quantify the true prevalence of BD in fibromyalgia patients. That said,
the high odds ratio is difficult to ignore, especially given the
clinical relevance of the comorbidity,” Kudlow said.
Another perspective on the results
In Sweden, fibromyalgia is viewed at least in part as a
stress disorder, according to Bo Karlsson, MD, PhD, from Uppsala
University. Dr. Karlsson has been investigating fibromyalgia causes and
treatments for the past 12 years. After reading an advance copy of the
study by Dr. Kudlow and colleagues, Karlsson called the finding,
“interesting.”
“It´s definitely of clinical value to look for bipolar
disorder to avoid treatment failures with antidepressant drugs,” Dr.
Karlsson said in an email interview. “You have certainly evaluated if
your FM patient is depressed. It´s of importance to screen for manic
episodes as well, to minimize the side effect from antidepressant drugs
and make a choice of treatment with mood stabilizers.”
Using antidepressants to treat bipolar disorder
The role of antidepressants in the treatment of bipolar
disorder has been controversial, with clinical studies showing
inconsistent results. Some have found that certain antidepressants may
increase the risk of rapid cycling between mania and depression,
hypomania, mania, and mixed states.3
In 2013, the American Journal of Psychiatry issued a
warning about using SSRIs and SNRIs to treat people with bipolar
disorder. The evidence received a C rating, which indicates that
although the conclusions made clinical sense and were probably
applicable in context, there were also some inconsistencies and only a
modest clinical impact. The task force concluded that the risk of mood
switching is considered to be higher and more severe in bipolar I than
bipolar II patients, and somewhat greater with tricyclics, tetracyclics,
and some SNRIs than with most modern antidepressants.4
Conclusion
Dr. Kudlow suggests that clinicians be cautious about
prescribing certain antidepressants for their FM patients because of
these concerns, and the potentially significant prevalence of BD.
“The main feedback I think I would give is to make sure you
screen your patients diagnosed with fibromyalgia for bipolar disorder
symptoms,” Dr. Kudlow said. "It is really as simple as administering the
Mood Disorder Questionnaire. It's 16 questions and it gives a pretty
good sense of the risk of bipolar disorder."
Dr. Kudlow notes that additional studies are needed to
accurately determine the prevalence of BD in FM. “A longitudinal cohort
study is needed where we follow a group of people diagnosed with bipolar
disorder without fibromyalgia, and groups with fibromyalgia and/or
other chronic pain disorders without bipolar disorder, over time. This
will allow us to measure the incidence of the fibromyalgia and bipolar
disorder comorbidity,” Dr. Kudlow said.
“The only way to definitively answer these important
questions is with longitudinal cohort studies, but unfortunately this
will require a lot of time and money,” Dr. Kudlow concluded.
Reference
1. Prevalence of fibromyalgia and co-morbid bipolar disorder: A systematic review and meta-analysis Kudlow, P.A. et al. Journal of Affective Disorders , Volume 188 , 134 - 142
2. “Living with Fibromyalgia, Drugs Approved to Manage Pain,” http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm107802.htm - approved
3. “What is bipolar disorder?” National Institute of Mental Health. http://www.nimh.nih.gov/health/publications/bipolar-disorder-in-adults/index.shtml
4. Pacchiarotti, et al. “The International Society for Bipolar Disorders (ISBD) Task Force Report on Antidepressant Use in Bipolar Disorders”. http://ajp.psychiatryonline.org/doi/full/10.1176/appi.ajp.2013.1302018
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