Does Fibromyalgia Mask Spondyloarthritis?

June 21, 2017

With clinical overlap, study findings suggest vigilance and an active search for underlying inflammatory disorders.

In patients with a diagnosis of fibromyalgia syndrome, radiographic evidence of axial spondyloarthritis is common. Because the conditions may have considerable clinical overlap, the fibromyalgia syndrome may mask the underlying spondyloarthritis.[[{"type":"media","view_mode":"media_crop","fid":"60952","attributes":{"alt":"","class":"media-image media-image-right","id":"media_crop_4041744426524","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"7697","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","style":"height: 240px; width: 190px; border-width: 0px; border-style: solid; margin: 5px; float: right;","title":" ","typeof":"foaf:Image"}}]]

Centralized pain or “fibromyalgianess” (polysymptomatic distress) may be responsible for observed differences in spondyloarthritis pain and inflammatory damage between men and women.

Jacob Ablin and colleagues in Israel pointed out that fibromyalgia syndrome is classically considered a noninflammatory widespread pain disorder with pathogenic characteristics very different from those of spondyloarthritis. Although the conditions differ in etiology, they appear to coexist with some frequency, which the authors noted in a recent Arthritis Care & Research article.

Current guidelines suggest that once a diagnosis of fibromyalgia syndrome is made, aggressive investigations should be avoided to minimize further discomfort or complication. This suggestion confounds the discovery of underlying or concurrent inflammatory disease and may lead to underdiagnosis.

This study’s findings suggest that physicians remain vigilant and actively search for underlying inflammatory disorders in patients with fibromyalgia syndrome.

An increased prevalence of secondary fibromyalgia syndrome has been described in female patients with spondyloarthritis. No investigation into the converse has been made.

Attention has been paid to gender differences in patients with axial spondyloarthritis, but little effort has been made to uncover the mechanisms beneath differing clinical manifestations in men and women.

The study

Ultimately, 99 patients who met American College of Rheumatology 1990 criteria for fibromyalgia syndrome were included. Patients were examined by MRI and classified as having features of spondyloarthritis or not, based on the Assessment of Spondyloarthritis International Society criteria.

Results

Regression analysis revealed a positive correlation between C-reactive protein levels and axial spondyloarthritis, with an odds ratio of 5.1; 31.5% of subjects had an elevated level.

HLA-B27 genetic positivity was seen in 3.2% of enrolled patients.

Among studied patients with fibromyalgia syndrome, 8.1% had sacroiliitis and 10.2% met Assessment of Spondyloarthritis International Society criteria for axial spondyloarthritis.

A significant number of patients with fibromyalgia possessed radiographic changes that indicated inflammatory involvement; 17% demonstrated erosions and 25% had subchondral sclerosis. Further imaging revealed evidence of bone marrow edema and fat deposition in 17% and 7.9% of subjects, respectively.

Implications for physicians

Many patients with fibromyalgia syndrome also have spondyloarthritis based on the Assessment of SpondyloArthritis International Society criteria.

Clinicians should recognize the overlap of fibromyalgia syndrome and spondyloarthritis when present so as to not miss the opportunity to treat the inflammatory disease as well.

The effects of fibromyalgia syndrome on activity indices, such as the Fibromyalgia Impact Questionnaire and the Bath Ankylosing Spondylitis Functional Index, are worth emphasizing.

Inflammatory indices, such as C-reactive protein levels, should be collected routinely in patients with fibromyalgia to screen for underlying inflammatory disease.

Careful clinical judgment is suggested when attempting to differentiate between central pain syndromes like fibromyalgia and inflammatory disease because MRI is still costly and time consuming.

Disclosures:

AbbVie supplied an investigational grant for this study.

References:

Jacob N. Ablin, Iris Eshed, Mark Berman, et al. “Prevalence of axial spondyloarthritis among patients with fibromyalgia: a magnetic resonance imaging study with application of the Assessment of SpondyloArthritis International Society Classification Criteria.” Arthritis Care & Research. Vol. 69, No. 5, May 2017, pp 724–729 DOI 10.1002/acr.22967