Recent studies have suggested that fibromyalgia is inaccurately diagnosed in the community, and that ~75% of persons reporting a physician diagnosis of fibromyalgia would not satisfy published criteria. To investigate possible diagnostic misclassification, we compared expert physician diagnosis with published criteria.
In a university rheumatology clinic, 497 patients completed the Multidimensional Health Assessment Questionnaire (MD-HAQ) and the 2010 American College of Rheumatology preliminary diagnostic criteria modified for self-administration during their ordinary medical visits. Patients were evaluated and diagnosed by university rheumatology staff.
Of the 497 patients, 121 (24.3%) satisfied the fibromyalgia criteria, while 104 (20.9%) received a clinician International Classification of Diseases (ICD) diagnosis of fibromyalgia. The agreement between clinicians and criteria was 79.2%. However, agreement beyond chance was only fair (κ = 0.41). Physicians failed to identify 60 criteria-positive patients (49.6%) and incorrectly identified 43 criteria-negative patients (11.4%). In a subset of 88 patients with rheumatoid arthritis (RA), the kappa value was 0.32, indicating slight to fair agreement. Universally, higher polysymptomatic distress scores and criteria-based diagnosis were associated with more abnormal MD-HAQ clinical scores. Women and patients with more symptoms but fewer pain areas were more likely to receive a clinician's diagnosis than to satisfy fibromyalgia criteria.
There is considerable disagreement between ICD clinical diagnosis and criteria-based diagnosis of fibromyalgia, calling into question ICD-based studies. Fibromyalgia criteria were easy to use, but problems regarding clinician bias, meaning of a fibromyalgia diagnosis, and the validity of physician diagnosis were substantial.