Fibromyalgia May Cause Doctors to Overestimate Severity of Spondyloarthritis

Fibromyalgia May Cause Doctors to Overestimate Severity of Spondyloarthritis

Physicians tend to overestimate disease activity in patients with spondyloarthritis who also have fibromyalgia, a recent study suggested, echoing earlier findings on the subject.

The study, “Fibromyalgia in Spondyloarthritis: Effect on Disease Activity Assessment in Clinical Practice,” published in the Journal of Rheumatology, underscores that physicians need to be aware that the co-occurrence of fibromyalgia may skew assessments, as an overestimation of disease activity may cause patients to be treated with too high doses of anti-inflammatory drugs.

Spondyloarthritis is the second most common inflammatory rheumatic disease, causing arthritis of the joints, as well as inflamed and painful entheses — the tissue where a tendon connects to the bone. The condition, however, also shares symptoms with fibromyalgia, such as pain, stiffness, and fatigue, and researchers believe that the two diseases might be related. These similarities also lead to difficulties in diagnosis and disease evaluations.

Since assessment of spondyloarthritis draws mainly on patient-based measures, researchers from the Centre Hospitalier Lyon-Sud, in France, evaluated if the co-occurrence of the disease with fibromyalgia affects clinical assessments.

The research team recruited 103 patients with spondyloarthritis, including 18 who also had fibromyalgia. Researchers recorded patient characteristics, and evaluated patients with a number of different tools, including the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), and the Ankylosing Spondylitis Disease Activity Score/C-reactive protein (ASDAS-CRP).

While those with both spondyloarthritis and fibromyalgia had higher disease activity scores when assessed with the BASDAI tool, the ASDAS-CRP assessment did not differ between patients with and without fibromyalgia. Researchers, however, noted that a median ASDAS-CRP score corresponded to higher levels of disease activity in patients with both conditions.

Based on these differences, the team concluded that disease activity measured by BASDAI may overestimate the severity of disease, leading physicians to prescribe too high doses of anti-inflammatory drugs, with unnecessary side effects as a consequence.

Earlier this year, Fibromyalgia News Today reported that patients with co-occurring spondyloarthritis and fibromyalgia have more severe symptoms compared to patients without fibromyalgia. The study used the BASDAI tool to assess symptoms and, like the present study, also concluded that fibromyalgia may impact assessments of severity of spondyloarthritis.