Fibromyalgia does not fit within the main arthritis classifications but is considered a chronic pain condition. The primary symptoms are widespread pain throughout the body and fatigue. Recent revisions to diagnosis now focus on four criteria.1  
1)    Generalized pain, defined as pain in at least 4 of 5 regions is present.
2)    Symptoms have been present at a similar level for at least 3 months.
3)    Widespread pain index (WPI) ≥7 and symptom severity scale (SSS) score ≥5 OR WPI of 4-6 and SSS score ≥9.
4)    A diagnosis of fibromyalgia is valid irrespective of other diagnoses. A diagnosis of fibromyalgia does not exclude the presence of other clinically important illnesses.

The cause of fibromyalgia is not known, but current theories include a higher sensitivity to pain. Fibromyalgia can occur by itself, although it can also accompany another form of arthritis such as rheumatoid arthritis or spondyloarthritis.

Prevalence of Fibromyalgia

Estimates of fibromyalgia range from 4 million (2% of the adult population)2 to 10 million (5% of adult population).3 Fibromyalgia is most prevalent in females, with up to 90% of incident cases females. It is also more common among older members of the population.

 
Healthcare Utilization

Hospitalization

Just under one-half million (442,000) hospitalizations in 2013 had a diagnosis of fibromyalgia, representing 1.5% of hospital visits for any diagnoses, and accounting for 1.4% of all hospital charges billed. Females accounted for 89% of the hospitalizations, with those age 45 to 64 accounting for nearly half (48%) of the discharges. Fibromyalgia is diagnosed along with connective tissue disease (11.1%), joint pain (8.2%), and rheumatoid arthritis (7.1%) when multiple diagnoses are made. Hospital stays are similar to discharges for any diagnoses in length of stay and mean charges. Discharge to home is most common.  (Reference Table 3A.3.1.0.1 PDF CSV; Table 3A.3.1.0.2 PDF CSV; Table 3A.3.0.2 PDF CSV; Table 3A.3.1.1.1 PDF CSV; Table 3A.3.1.3.1 PDF CSV)

Ambulatory Care Visits

Fibromyalgia diagnoses were made in 0.8% of all ambulatory care visits for any diagnosis, accounting for 7.7 million ambulatory visits. Ambulatory visits were made more frequently by females (79%), those aged 45-64 years (52%), non-Hispanic whites (74%), and by those living in the Northeast region (rate of 3.8/100 persons versus 3.1/100 for all regions). (Reference Table 3A.3.2.0.1 PDF CSV; Table 3A.3.2.0.2 PDF CSV; Table 3A.3.2.0.3 PDF CSV; and Table 3A.3.2.0.4 PDF CSV)

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Economic Burden

Economic costs were not calculated for fibromyalgia.

• 1. Wolfe F, Clauw DJ, Fitzcharles MA, et al. 2016 revisions to the 1010/2011 fibromyalgia diagnostic criteria. Seminars in Arthritis Rheum 2016;46(3):319-329.
• 2. Center for Disease Control. Fibromyalgia.  https://www.cdc.gov/arthritis/basics/fibromyalgia.htm . Accessed September 25, 2017.
• 3. National Fibromyalgia Association. About fibromyalgia. http://www.fmaware.org/about-fibromyalgia/prevalence/. Accessed September 25, 2017.