Thursday, November 12, 2015

Fibromyalgia at the ACR 2015 Meeting in San Francisco / Diagnosis

There were quite a number of abstracts, posters, and talks on fibromyalgia at the ACR 2015 Annual Meeting in San Francisco. I’d like to comment on these abstracts concerning criteria and diagnosis.

Frederick Wolfe and colleagues looked at 514 patients in the ACR 2010 criteria study to compare physician based and patient based criteria. There was good agreement in physician and patient fibromyalgia diagnosis and other measures. “There is acceptable agreement in diagnosis and PSD [polysymptomatic distress scale] for research, but insufficient agreement for clinical decisions and diagnosis.”

Frederick Wolfe and Winfried Häuser looked at misclassifications of the Fibromyalgia 2010 Criteria as the elimination of wide spread pain could lead to the inclusion of patients without generalized pain and therefore could favour a bias for psychological symptoms. The authors concluded: “When used in settings where non-WSP and regional or psychiatric diagnoses are substantially increased, FM criteria will “misclassify” persons. This occurs because there is no reliable gold standard fibromyalgia definition. The solution to this type of misclassification is to use the most appropriate clinical diagnosis (e.g., regional arm pain or rheumatoid arthritis) and indicate the patient also satisfied fibromyalgia criteria.”

Gary J. Macfarlane and colleagues “have investigated whether associations with features are stronger in persons with chronic widespread pain (CWP) compared to multi-site pain (MSP).” They concluded: “We have found that a definition of MSP as at least 8 (of 35) pain sites consistently results in a similar population prevalence to that of CWP, and that the defined groups are similar but not the same. The results suggest that amongst persons with MSP, those with CWP are significantly more likely to exhibit features typical of fibromyalgia.”

Xenofon Baraliakos and colleagues “examined similarities and differences between axSpA and FM using different sets of classification criteria and to assess the severity of wide-spread pain in both diseases.” The authors concluded: “Importantly, no FM patients fulfilled ASAS classification criteria. Only a small proportion of patients with axSpA fulfilled any of the FM classification criteria. There was less overlap between patients with FM, axSpA and RA using the 1990 criteria as compared to the more sophisticated 2010 FM criteria. … Some patients with widespread pain may have underlying axSpA – this differential diagnosis needs to be taken into account when dealing with the diagnosis of FM in daily practice.”

All in all, these studies show, how difficult it still is to correctly diagnose fibromyalgia. There aren’t easy criteria that work like a cook book, so the expertise of rheumatologists is still warranted. The studies imply that the diagnosis should be weighed against other diseases or the possibility of concomitant diseases. And I think these studies also tell us not to diagnose fibromyalgia without chronic widespread pain.

Wolfe F, Fitzcharles MA, Goldenberg D, Häuser W, Katz RS, Mease PJ, Russell A, Russell J, Walitt B. A Comparison of Physician Based and Patient Based Criteria for the Diagnosis of Fibromyalgia [abstract]. Arthritis Rheumatol. 2015; 67 (suppl 10). Accessed November 12, 2015.

Wolfe F, Häuser W. When Fibromyalgia Criteria Misclassify [abstract]. Arthritis Rheumatol.2015; 67 (suppl 10). Accessed November 12, 2015.

Macfarlane GJ, Dean LE, Bennett R, Crofford LJ, Ayorinde A, Fluess E, Clauw DJ, Fitzcharles MA, Goldenberg D, Paiva E, Staud R, Arnold L. Defining Pain for Fibromyalgia Criteria: Multi-Site or Widespread? an Analysis of Data from Four UK Population-Based Studies [abstract]. Arthritis Rheumatol. 2015; 67 (suppl 10). Accessed November 12, 2015.

Baraliakos X, Regel A, Kiltz U, Menne HJ, Dybowski F, Igelmann M, Kalthoff L, Krause D, Saracbasi E, Schmitz-Bortz E, Braun J. Patients with Fibromyalgia (FM) Do Not Fulfill Classification Criteria for Axial Spondyloarthritis (axSpA) but Patients with Axspa May Fulfill Classification Criteria for FM [abstract]. Arthritis Rheumatol. 2015; 67 (suppl 10). Accessed November 12, 2015.

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