In patients with rheumatoid arthritis (RA) and concomitant fibromyalgia, disease activity scores may be artificially inflated due to pain and patient distress. Since disease activity score (Disease Activity Score 28, or DAS28) is one component of an algorithm clinicians use to help decide which treatment is best suited for their RA patients, it is important to remove confounding variables that could influence DAS28.

Ultrasonography is one tool that can be used to predict disease activity in patients with RA and can detect RA characteristics such as synovitis. A research team from Romania recently conducted a study with ultrasonography in patients with RA and fibromyalgia and determined that ultrasonography should be used to guide treatment decisions in these patients rather than rely solely on the DAS28.

“Ultrasonography… is a good marker of prognosis,” wrote Dr. Linda Jessica Ghib, lead author of “The Role of Ultrasonography in Assessing Disease Activity in Patients with Rheumatoid Arthritics and Associated Fibromyalgia,” which was published in Medical Ultrasonography. “The main aim of this study is to evaluate and to compare the ultrasonography and DAS28 scores between RA, RA and associated fibromyalgia, and fibromyalgia patients.”

All patients in the study were females diagnosed with RA and/or fibromyalgia. For every RA patient enrolled, the researchers enrolled a fibromyalgia patient and a patient with both RA and fibromyalgia. There were 30 patients in total. During patient examinations, the researchers collected DAS28 scores and conducted ultrasonography in the joints.

Results showed that patients with both RA and fibromyalgia had significantly higher DAS28 scores, with eight of the ten patients in that group classified as having high disease activity. Only four of the ten patients with RA alone had high disease activity scores. In fact, while one patient with fibromyalgia alone and two patients with RA alone had low disease activity scores, none of the fibromyalgia/RA patients had low disease activity scores.

This contrasted the scores obtained by ultrasonography. “Ultrasonography scores correlated moderately only with DAS28… in patients with RA, and not in patients with fibromyalgia/RA,” wrote the researchers. Scores were in fact inversely related in patients with fibromyalgia.

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Although DAS28 is a convenient way to assess disease activity in patients with RA, it may not be accurate for RA patients with fibromyalgia. Having fibromyalgia may artificially inflate DAS28, as RA patients and fibromyalgia/RA patients have similar ultrasonography characteristics despite differences in DAS28 scores. Therefore, ultrasonography may be necessary to conduct in fibromyalgia/RA patients when clinicians are determining the best mode of treatment for their patients.