The diagnosis of fibromyalgia as a discrete entity has typically been made using the American College of Rheumatology (ACR) 1990 classification criteria, which is widespread pain for more than 3 months and the presence of at least 11 of 18 tender points.
2 Widespread pain is defined as pain on both sides of the body, pain above and below the waist, and the presence of axial pain. The examiner identifies tender points by using the thumb to exert 4.0 kg pressure (sufficient to blanch the thumbnail) at each of the discrete tender points to elicit pain.
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The ACR diagnostic criteria were developed for research purposes but were gradually adopted for clinical diagnosis. Using these criteria for diagnosis is problematic for more than 1 reason. Few primary care physicians perform tender point examinations (or correctly perform tender point examinations).
19 The same can be said for many rheumatologists.
19 Additionally, the case definition of fibromyalgia has evolved in the past 20 years to include cognitive and other symptoms that are not included in the 1990 ACR criteria.
1 Finally, tender points are highly correlated with psychological distress and are absent in as many as 25% of patients who have fibromyalgia.
19,20 For these reasons, the ACR introduced a new provisional set of diagnostic criteria for fibromyalgia in 2010.
1 These proposed criteria do not require a tender point examination but rely on patient reports of widespread pain and other somatic symptoms. A patient satisfies the proposed diagnostic criteria if 3 conditions are met:
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The patient has a widespread pain index (WPI) of 7 or greater and symptom severity (SS) scale score of 5 or greater. Alternatively, a patient could meet criteria with a WPI of 3 to 6 and SS scale score of 9 or greater.
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Symptoms have been present at a similar level for at least 3 months.
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The patient does not have a disorder that would otherwise explain the pain.
The WPI is calculated by summing up patient reports of pain in 19 separate regions of the body.
1 The SS scale score is calculated by grading several symptoms (eg, pain, fatigue, awaking unrefreshed) on a severity scale from 0 (“no problem”) to 3 (“severe, pervasive, continuous, life-disturbing problems”).
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