Test Excludes Fibromyalgia in Patients With Rheumatic Disease

Norra MacReady

July 06, 2016

A simple questionnaire can help rheumatologists screen for fibromyalgia (FM) in patients with inflammatory rheumatic diseases, the authors of a new study report.

The findings suggest the test "has better performance for excluding the diagnosis of concomitant FM rather than confirming it," they write. "Its routine use would quickly exclude this condition and improve patient care."

The prevalence of FM is higher among people with inflammatory rheumatic diseases than in the general population, lead author Angelique Fan, MD, and colleagues write in an article published online June 15 in Rheumatology. Its symptoms mimic those of many inflammatory rheumatic illnesses and might prompt the physician to think treatment is ineffective or to exaggerate the severity of the rheumatic disorder, leading to overtreatment.

A reliable test to help physicians identify concomitant FM in this population might help prevent these pitfalls.

The Fibromyalgia Rapid Screening Tool (FiRST) is a self-administered questionnaire developed by the French Society of Rheumatology. It can quickly detect FM, with a sensitivity of 90.5% and a specificity of 85.7% in the general population, the authors write. However, until now it has been used only to discriminate between FM and other painful conditions. They studied its ability to help physicians detect concomitant FM in patients with inflammatory rheumatic disorders.

Dr Fan, from the Rheumatology Department, Délégation à la Recherche Clinique et à l'Innovation, CHU Gabriel-Montpied, Clermont-Ferrand, France, and colleagues conducted a cross-sectional, single-center study between September 2014 and April 2015. All patients coming to the rheumatology department of Clermont-Ferrand University Hospital for treatment of rheumatoid arthritis, spondyloarthritis, or connective tissue disease, and whose pain had persisted for at least 3 months, were invited to participate. The questionnaire findings were compared with the American College of Rheumatology (ACR) 90 criteria for FM and with the opinion of a rheumatologist who was blinded to each patient's FiRST results.

FiRST consists of six questions covering the six dimensions of FM: widespread pain, fatigue, pain characteristics, nonpainful abnormal sensations, functional somatic symptoms, and sleep and cognitive problems. Each question requires only a "yes" or "no" answer, with a "yes" being worth one point and a "no" worth zero points. One question, for example, asks whether patients have pain all over their body, whereas another asks whether the pain is accompanied by other sensations such as tingling or pins and needles. The highest possible score is 6, with a cutoff of 5 or more associated with the highest sensitivity and specificity for FM.

A total of 586 patients completed valid questionnaires, including 143 who scored at least 5 (24.4%; 95% confidence interval [CI], 21% - 28%). By comparison, the ACR 90 criteria detected only 52 cases of FM (8.6%), and the rheumatologist, 93 cases (15.4%). FiRST detected FM in 36 men (25.2% of cases) compared with three detected by the ACR 90 criteria (5.8%; P < .001), and 12 by the rheumatologist (13%; P = .05).

The test "detected ACR 90-defined FM patients with a sensitivity of 74.5% and a specificity of 80.4%," with a negative predictive value of 97% and a positive predictive value of 26.6%, the authors write. "These performance measures translate into 80% of patients being correctly classified (κ=0.3)."

FiRST showed a "reasonable" ability to discriminate between symptoms that were FM and not FM (receiver operating characteristic area under the curve, 0.86). Sensitivity did not vary by disease type, but FiRST was associated with lower specificity among people with connective tissue disease (P = .001).

Similarly, when compared with the rheumatologist's findings, FiRST had a sensitivity of 75.8%, a specificity of 85.1%, and concordance of 83.6% (κ = 0.49). The negative predictive value and positive predictive value were 95% and 48.3%, respectively. "This shows that the FiRST diagnosis is similar to that of a rheumatologist," the authors point out. Sensitivity was lower in the spondyloarthritis group than in the connective tissue disease group (P = .004), but, the authors note, distinguishing between spondyloarthritis and FM "is the most difficult because they have several signs in common."

Study limitations include the low proportion of patients in the sample who met ACR 90 criteria and the limited number and heterogeneity of patients with connective tissue disease. Also, the test was not as effective among these patients as it was in the general population.

Nevertheless, the authors write, FiRST "can be used by the rheumatologist in clinical practice in patients facing an apparent treatment failure and to rule out a potential FM diagnosis which could interfere with the treatment response."

This work received internal funding from the CHU of Clermont-Ferrand. The authors have disclosed no relevant financial relationships.

Rheumatology. Published online June 15, 2016. Abstract

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