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Clustering fibromyalgia patients helps inform therapeutic decisions: study

The study results, which suggest a step forward for individualized
patient therapy, were presented in a scientific poster today at the 30th
Annual Meeting of the American Academy of Pain Medicine.

Fibromyalgia
is a condition marked by many symptoms that include widespread pain,
fatigue, depression and sleep disturbances. However, not every
fibromyalgia patient experiences every symptom or to the same degree,
complicating therapeutic decisions.

“Currently, fibromyalgia is
ineffectively treated and heterogeneity is part of the problem,” said
lead study author, Ann Vincent, former medical director and now a
fulltime researcher with the Mayo Fibromyalgia Clinic in Rochester,
Minn.

 “When a patient comes into the clinic, there is no
standardized way to classify the heterogeneity in a way to understand
their most bothersome symptom. Different physicians have their own ad
hoc methods and choices of medications,” Vincent said. “What if we could
have a better way to assess patients by classifying the illness from
their perspective in terms of their most bothersome symptoms?”

Guided
by that research question, study investigators were the first to use
core symptom domains recommended by the fibromyalgia working group of
the Outcome Measures in Rheumatoid Arthritis Clinical Trials (OMERACT)
initiative to identify subgroups of patients with similar symptom
profiles. The OMERACT initiative develops and validates outcome measures
to assist with research in clinical trials.

The Institutional
Review Board of the Mayo Clinic approved the study, which was partially
funded by grants through the Mayo Clinic and the U.S. National
Institutes of Health.

“We were looking to cluster participants
according to their response to a comprehensive symptom questionnaire
package to identify groups of individuals who reported similar symptom
profiles,” Dr. Vincent said.

Included for analysis were 581
females with a mean age of 55.1, each with a fibromyalgia diagnosis. The
patients completed several outcome measures recommended by OMERACT as
follows: the Brief Pain Inventory, 30-item Profile of Mood States,
Medical Outcomes Sleep Scale, Multidimensional Fatigue Inventory,
Multiple Ability Self-Report Questionnaire, Fibromyalgia Impact
Questionnaire-Revised and Medical Outcomes Short Form-36.

The
study investigators then used a statistical technique that groups or
clusters similar observations or values to identify subgroups of
patients. What emerged from the data were four clusters, distinguished
by differences in symptomology and pain severity.

Patients in
Cluster 1 had the lowest average levels across all symptoms, and Cluster
5 had the highest levels. There were differences also between the
clusters that reflected moderate symptom levels – Clusters 2 and 3.
Cluster 2 patients had less depression, anxiety and dyscognition, also
known as the “fibro fog,” but had more pain, stiffness, dysfunction,
sleep disturbances and fatigue than the patients in Cluster 3.  

Vincent,
who frequently studies fatigue and related symptoms in fibromyalgia
patients, said further study in other samples is needed to validate the
findings, after which, the ability to target and tailor treatments to
specific symptoms could bring better outcomes.

For example,
Vincent said, if a patient’s scores place her in Cluster 1, in which
subjects scored comparatively low on all symptoms, a clinician might
consider initial management with non-pharmacological treatments, such as
cognitive-behavioral therapy, exercise, physical therapy and education
for self-management of symptoms, with the option of adding
pharmacological therapies if initial treatment response fails.

Conversely,
she explained, patients in Cluster 4, marked by higher scores on
symptoms, might be preferentially triaged to intensive pain
rehabilitation, given that regular outpatient treatment is frequently
ineffective in this patient population.

“Obviously, this needs to be studied,” Vincent said, “and this is our next step.”