There may be substantial disparity between diagnoses of fibromyalgia based on criteria vs International Classification of Diseases standards, according to a study published in Arthritis Care & Research.

A total of 497 consecutive patients attending a university rheumatology clinic were asked to complete the Multidimensional Health Assessment Questionnaire, the 2010 American College of Rheumatology preliminary diagnostic criteria for fibromyalgia (including the 2011 modification for self-report).

In this cohort, 24.3% of the patients were considered to satisfy the criteria for fibromyalgia, and 20.9% were given a fibromyalgia diagnosis by a clinician, based on International Classification of Diseases criteria, corresponding to 79.2% agreement between criteria and clinicians (κ, 0.41). Physicians failed to diagnose fibromyalgia in 60 patients (49.6%) deemed to have fibromyalgia according to criteria, and incorrectly diagnosed fibromyalgia in 43 criteria-negative patients (11.4%). Of patients clinically diagnosed with fibromyalgia, 58.7% were found to satisfy criteria for the disease, and of 393 patients not diagnosed with fibromyalgia by physicians, 15.3% were found to satisfy the criteria, a rate that the researchers considered to be clinically significant.

In a subset of 88 patients with rheumatoid arthritis, the clinicians and criteria agreed in 84.1% of cases (fair agreement; κ, 0.32). Of 13 patients with rheumatoid arthritis and criteria-positive fibromyalgia, only 5 (38.5%) were diagnosed by clinicians.

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Women and those with more symptoms (but fewer pain areas) were found to be less likely to satisfy fibromyalgia criteria than to be diagnosed for the condition by a clinician.

Study limitations include the study setting in a rheumatology clinic, where disagreement between criteria-based and clinician diagnosis may have been less severe than in a primary care setting.

“It is likely that misdiagnosis [of fibromyalgia] is a public health problem and one that can lead to overdiagnosis and overtreatment, as well as to inappropriate treatment of individuals not recognized to have fibromyalgia symptoms,” noted the study authors.

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Reference

Wolfe F, Schmukler J, Jamal S, et al. Diagnosis of fibromyalgia: disagreement between fibromyalgia criteria and clinician-based fibromyalgia diagnosis in a university clinic. Arthritis Care Res. 2019;71(3):343-351.