DENVER – Fibromyalgia syndrome commonly occurred in patients with ankylosing spondylitis who were reviewed at one U.S. center, and when the two coexisted ankylosing spondylitis disease severity significantly increased.
In the study’s 62 patients with confirmed ankylosing spondylitis (AS), 27 (44%) also met the 2010 American College of Rheumatology diagnostic criteria for fibromyalgia syndrome, Sherilyn Diomampo, MD, said at the annual meeting of the Spondyloarthritis Research and Treatment Network. The fibromyalgia rate in these AS patients was substantially above prior reports of fibromyalgia prevalence rates in the range of 10%-15%, said Dr. Diomampo, a rheumatologist at MetroHealth Medical Center in Cleveland.
Mitchel L. Zoler/Frontline Medical News
Dr. Sherilyn Diomampo
Patients with both disorders also had substantially higher scores across the board for all the measures of AS severity that Dr. Diomampo and her associates evaluated. For example, scores on the Bath AS Disease Activity Index averaged 6.8 in the patients with fibromyalgia and 3.8 in those without fibromyalgia. (A BASDAI score of 4.0 or higher generally suggests suboptimal disease control.) The average score of the AS Disease Activity Score using C-reactive protein (CRP) as the serum marker of inflammation was 4.2 in the subgroup with fibromyalgia and 2.8 in those without. (An ASDAS score of 3.5 or higher denotes high or very high disease activity. A score reduced by at least 1.1 indicates a clinically important improvement.) All these between-group differences were statistically significant.
Other measures of AS severity that were significantly higher with fibromyalgia included patient global self assessment, physician global assessment, average serum levels of CRP, and the average erythrocyte sedimentation rate.
The 2010 ACR diagnostic criteria for fibromyalgia syndrome used by Dr. Diomampo and her associates in their analysis require a patient to have a widespread pain index of at least 7 and symptom severity of at least 5, or alternatively, a widespread pain index of 3-6 and symptom severity of at least 9 (Arthritis Care Res. 2010 May;62[5]:600-10). In addition, for this study, the researchers stipulated that diagnosis of concomitant fibromyalgia meant patients had their fibromyalgia symptoms in place for at least 3 months, and the examining clinician could not attribute the patient’s pain to AS.
Using linear regression models with the widespread pain index and the symptom severity as the dependent variables, the researchers failed to see any statistically significant relationship between either of these two determinants of fibromyalgia severity and five different measures of AS severity, including the BASDAI and the ASDAS. In short, the assessment tools used to measure AS severity showed no ability to also measure the core characteristics of fibromyalgia, Dr. Diomampo said.
Overall, patients in the study averaged about 49 years old. The analysis showed a significantly higher rate of African-American patients in the fibromyalgia group, 63%, compared with a 37% rate of African Americans in those with AS and no fibromyalgia. The presence of acute, anterior uveitis was 27% among those with fibromyalgia and 73% of those with AS and no fibromyalgia. One notable similarity between the two subgroups was the percentage on treatment with a tumor necrosis factor inhibitor: 52% among those with concurrent fibromyalgia and 49% among those with AS alone.
Dr. Diomampo had no disclosures.
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