In a recently published article in Arthritis Care & Research, Wolfe et al reported on a large-scale study designed to develop new and more clinically useful diagnostic criteria for fibromyalgia (FM) (Wolfe F, Clauw DJ, Fitzcharles MA, Goldenberg DL, Katz RS, Mease P, et al. The American College of Rheumatology preliminary diagnostic criteria for fibromyalgia and measurement of symptom severity. Arthritis Care Res [Hoboken] 2010;62:600–10).
The study included patients (n = 1,002) with local and widespread pain from 55 centers. Using the 1990 American College of Rheumatology (ACR) FM criteria, including the assessment of tender points, the patients were diagnosed as having FM (Wolfe F, Smythe HA, Yunus MB, Bennett RM, Bombardier C, Goldenberg DL, et al. The American College of Rheumatology 1990 criteria for the classification of fibromyalgia: report of the Multicenter Criteria Committee. Arthritis Rheum 1990;33:160–72). Widespread pain was assessed by body pain drawing, and extensive questionnaires were applied. After a series of analyses, Wolfe et al concluded that a widespread pain index was the best predictor of FM. When this index was excluded from the analysis, key predictors of FM were nonrefreshing sleep, fatigue, cognitive difficulties, and a host of somatic symptoms. These 4 variables were then combined into a symptom severity scale, which ranged from 0–12. This symptom severity scale highly correlated with both the tender point count and the widespread pain index. The combination of the symptom severity scale and the widespread pain index identified 80.9% of the FM cases previously diagnosed by the 1990 ACR criteria. Furthermore, the symptom severity scale was useful for identifying previously diagnosed FM in patients who no longer satisfied ACR criteria. In phase 2 of their study, Wolfe et al collected the widespread pain index and symptom severity scale scores and reported that they performed well for diagnosing FM.
Wolfe and colleagues promote new diagnostic criteria that are almost as good (80% correct classification) as the previous criteria. The irony of this approach is that these 1990 ACR criteria had been previously disparaged by the same authors. Therefore, it is hard to consider this an advance of the clinical science.
Wolfe and colleagues are to be commended for this attempt at simplifying the diagnostic criteria for FM for general practitioners and specialists alike. Most of us will agree that the 1990 ACR criteria for FM lacked important illness features such as fatigue, morning stiffness, disturbed sleep, affective distress, etc. Wolfe et al remedied this omission by including several of these features, such as nonrestorative sleep, fatigue, and dyscognition, into the new criteria. Nevertheless, there is a glaring omission of well-known mechanistic FM features, such as hyperalgesia, central sensitization, or dysfunctional pain modulation.
We also doubt that the new criteria can provide more precision (specifically for characterization of FM subgroups) mostly because of the vagueness of the proposed criteria (fatigue, dyscognition, and nonrestorative sleep). Also, the somatic symptom list is extremely broad (41 somatic symptoms), and the symptoms are ordered by neither relevance nor predictive value, etc., supposedly contributing equally to FM. In conclusion, whether or not these new criteria are easy to apply by practicing physicians will require empirical testing. Unfortunately, the new criteria are imprecise, ill-defined, lack mechanistic features, and are completely symptom focused. They also subscribe to the same circular logic as the 1990 ACR criteria. Would it be better to teach physicians how to test tender points and therefore keep the old criteria? New criteria for FM are needed, but we doubt that Wolfe and colleagues have made the necessary quantum leap to advance this important issue.