Fibromyalgia syndrome is a diagnosis of exclusion. That means before doctors can give you a fibromyalgia diagnosis, they need to rule out a host of other conditions with similar symptoms. Typically, they'll order blood tests for hypothyroidism, infections, polymyalgia rheumatica, rheumatoid arthritis or lupus. Doctors may also order other lab and imaging tests.
Fibromyalgia is typically diagnosed and treated by rheumatologists. The American College of Rheumatology (ACR) in 1990 established the first diagnostic criteria for fibromyalgia. However, in May 2010 it published new provisional criteria, not to replace the old ones but to address certain limitations in the 1990 criteria. The goal is to provide a more practical approach that allows doctors to better monitor symptoms and disease severity. It remains to be seen how long it will take for doctors to begin using the new criteria.
1990 Fibromyalgia Diagnostic Critieria
Under the 1990 criteria, pain was the only symptom mentioned. Once other possible conditions were ruled out, a fibromyalgia diagnosis required:
- Pain in all four quadrants of the body and in the axial skeleton (bones of the head, throat, chest and spine) that's been present on a more or less continuous basis for at least three months.
- Pain in at least 11 of 18 tender points, which are specific spots on the body that hurt when pressure is applied. (See diagram, top right.)
The tender-point exam has been criticized for being too subjective. Some studies showed it had only about 75% sensitivity as well.
2010 Fibromyalgia Diagnostic Criteria
The new criteria take into account more symptoms and provide a method for monitoring symptom severity. They also provide some flexibility; one weakness of the tender point exam is that the pain threshold can fluctuate, meaning that the same person can have different results at different times. The researchers behind this method say the new criteria are about 88% accurate.
As with the old criteria, other possible conditions must be ruled out, and symptoms must have been present for at least 3 months. They also include 2 new methods of assessment: the widespread pain index (WPI) and the symptom severity (SS) scale score.
The WPI lists 19 areas of the body and you say where you've had pain in the last week. You get 1 point for each area, so the score is 0-19.
For the SS scale score, the patient ranks specific symptoms on a scale of 0-3. These symptoms include:
- Waking unrefreshed
- Cognitive symptoms
- Somatic (physical) symptoms in general (such as headache, weakness, bowel problems, nausea, dizziness, numbness/tingling, hair loss)
The numbers assigned to each are added up, for a total of 0-12.
For a diagnosis you need EITHER:
- WPI of at least 7 and SS scale score of at least 5, OR
- WPI of 3-6 and SS scale score of at least 9
A PDF document with the full criteria is available online. It includes the 19 areas in the WPI and a longer list of somatic symptoms: Fibromyalgia Diagnostic Criteria.
Who Diagnoses Fibromyalgia?
Since the 1990s, fibromyalgia primarily has been treated by rheumatologists, but now that it's being regarded more as a neurological condition, some neurologists also are treating it. Even so, it can be difficult to find a doctor who's willing and able to effectively diagnose and treat fibromyalgia.
A lot of questions and problems can come up along the road to diagnosis. This article can help you navigate some of the common ones:
American College of Rheumatology, 2007. "Fibromyalgia"
Wolfe F, et al. Arthritis Care & Research. 2010 May;62(5):600-10. The American College of Rheumatology preliminary diagnostic criteria for fibromyalgia and measurement of symptom severity.