Article
Patients with fibromyalgia (FM) do not fulfill classification criteria for axial spondyloarthritis (axSpA) but patients with axSpA may fulfill classification criteria for FM
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Authors
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Xenofon Baraliakos
- Rheumazentrum Ruhrgebiet, Herne
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Andrea Regel
- Rheumazentrum Ruhrgebiet, Herne
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Uta Kiltz
- Rheumazentrum Ruhrgebiet, Herne
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David Kiefer
- Rheumazentrum Ruhrgebiet, Herne
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Hans-Jürgen Menne
- Rheumatologische Schwerpunktpraxis Dortmund, Internistische Rheumatologie, Dortmund
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Friedrich Dybowski
- Rheumapraxis Ruhr, Herne
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Manfred Igelmann
- Praxis, Bochum
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Ludwig Kalthoff
- Internistisch-Rheumatologische Schwerpunktpraxis, Herne
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Dietmar M. J. Krause
- Internistische und rheumatologische Gemeinschaftspraxis, Gladbeck
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Ertan Saracbasi-Zender
- Rheumazentrum Ruhrgebiet, Herne
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Elmar Schmitz-Bortz
- Rheumatologische und Osteologische Schwerpunktpraxis Hattingen, Hattingen
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Jürgen Braun
- Rheumazentrum Ruhrgebiet, Herne
| Published: | September 1, 2015 |
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Outline
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Introduction: The ASAS classification criteria for axSpA have been challenged because FM patients could easily fulfill their clinical arm, which could lead to overdiagnosis of axSpA and wrong treatment decisions. Here we studied similarities and differences between axSpA and FM using different classification criteria and assessed the severity of wide-spread pain in both diseases.
Methods: Patients were prospectively included if diagnosed with axSpA or FM. Patients with rheumatoid arthritis (RA) were also included as controls. Patients on anti-TNF treatment were excluded.
Results: Overall, 214 patients were included: 93 with FM (7.5% HLA B27+), 91 with axSpA (79.1% HLA-B27+), 30 with RA (53.3% seropositive). The mean age was 50.7±9.1, 43.0±12 and 58.4±11.9 years, respectively, and the mean symptom duration was comparable: 6.6±6.9, 6.4±7.8 and 6.2±11.3, respectively. Expectedly, the gender ratio differed: FM and RA patients were mostly female (93.4% and 76.7%, respectively), as compared to axSpA patients (28.3%). The ASAS classification criteria were not fulfilled by any FM patient. In contrast, the 1990 and 2010 FM criteria were fulfilled by 98.3% and 100% of patients with FM, but also by 14.3% and 34.1% of axSpA (no differences between AS and nr-axSpA) and 30% and 46.7% of RA patients, respectively. The Fibromyalgia impact questionnaire (FIQ) values were 69.5±13.0, 45.4±19.3 (p<0.001) and 49.9±22.8, respectively, while the Health Assessment Questionnaire (HAQ) values were 1.7±0.5, 1.2±0.5 (p<0.001) and 1.6±0.8, for FM, axSpA and RA, respectively. FM patients reported the highest pain scores on a 0-10 numeric rating scale: 7.0±1.7 vs. 6.0±1.9 and 6.1±1.9 in axSpA and RA patients, respectively, while mean CRP values (mg/dl) were higher in axSpA (1.1±1.3) and RA (0.6±0.9) patients vs. FM (0.4±0.4) (both p<0.001).
Conclusion: 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. FM patients reported higher pain scores and more functional deficits. The differential diagnosis of axSpA needs to be taken into account when dealing with the diagnosis of FM in daily practice.
