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Painful Partners: Spondyloarthritis and Fibromyalgia

The implications for disease activity and quality of life when these disorders coexist.

Key points
• Approximately 1 in 5 patients with axial spondyloarthritis met the diagnostic criteria for fibromyalgia as well.

• Patients with spondyloarthritis who also met the criteria for fibromyalgia had higher disease activity, more comorbidities, markedly poorer quality of life, and significant work disruption compared to those without fibromyalgia.

• Extra-spinal and inflammatory measures did not differ between spondyloarthritis sufferers who met the diagnostic criteria for fibromyalgia and those who did not.

The prevalence of fibromyalgia is higher among those with inflammatory rheumatic disease in general than among the population at large. Macfarlane and colleagues1 in the United Kingdom point out that distinguishing axial spondyloarthritis from fibromyalgia is problematic, since the American College of Rheumatology included axial skeletal pain in the diagnosis of the latter.

These researchers note, "FM may distort responses to some of the key patient-reported measures used in axial SpA, such as the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and Bath Ankylosing Spondylitis Functional Index (BASFI)."1

The FDA recognized a shortfall in the development of effective drug therapy for patients who had either positive changes only on MRI or positivity for HLA-B27 in conjunction with other clinical and laboratory features characteristic of spondyloarthritis.

Because of these factors, the researchers sought to explore the overlap between axial spondyloarthritis and fibromyalgia and to distinguish between the conditions in an effort to develop treatment strategies that may work together. They recently presented their findings in Arthritis & Rheumatology.

The study
The authors utilized the British Society of Rheumatology Biologics Register in Ankylosing Spondylitis (BSRBR-AS), a prospective cohort study, to identify patients in the UK with axial spondyloarthritis. Various established measures were employed to determine clinical manifestations, disease severity, and shared criteria for fibromyalgia. Ultimately, 1504 patients were included.

The results
• 82.2% of subjects were HLA-B27 positive.

• 1 in 6 subjects were current smokers.

• 69.2% of subjects met the modified New York criteria for axial spondyloarthritis, and an additional 26.5% met the Assessment of Spondyloarthritis International Society criteria.

• 20.7% of subjects met criteria for fibromyalgia (P = .006).

• More female subjects than male met fibromyalgia criteria (26.1% vs 18.2%; P < .001).

• HLA-B27-positive patients were less likely than HLA-B27-negative patients or those not tested to have fibromyalgia (P < .001).

• Patients with spondyloarthritis who met the criteria for fibromyalgia had worse indices of disease activity, function, metrology, and global status; reported significantly worse quality of life and higher rates of depression and anxiety; generally had higher body mass index; and reported significantly greater work time missed.

Implications for physicians
• Significant numbers of patients with axial spondyloarthritis probably have fibromyalgia as well.

• Because patients with spondyloarthritis who have fibromyalgia have more severe disease, clinicians should screen for co-occurrence and make every effort to treat both diseases in parallel.

• Since these two diseases have a large impact on quality of life and work, future research is needed to explore the best treatment options that address the interaction of the two.


The Arthritis Research UK provided funding for this project.


1. Macfarlane GJ, Barnish MS, Pathan E, et al. Co-occurrence and characteristics of patients with axial spondyloarthritis who meet criteria for fibromyalgia: results from a UK national register. Arthritis Rheumatol. 2017;69:2144-2150. doi: 10.1002/art.40185.