Predicting Disease Activity in Rheumatoid Arthritis with the Fibromyalgia Survey Questionnaire: Does the Severity of Fibromyalgia Symptoms Matter?

To determine if the degree of baseline fibromyalgia symptoms in patients with rheumatoid arthritis (RA), as indicated by the Fibromyalgia Survey Questionnaire (FSQ) score, predicts RA disease activity after initiation or change of a disease-modifying antirheumatic drug (DMARD).One hundred ninety-two participants with active RA were followed for 12-weeks after initiation or change of DMARD therapy. Participants completed the FSQ at the initial visit. The Disease Activity Score in 28 joints using the C-reactive protein level (DAS28-CRP) was measured at baseline and follow-up to assess RA disease activity. We evaluated the association between baseline FSQ score and follow-up DAS28-CRP. As a secondary analysis, we examined the relationship between the two components of the FSQ, the Widespread Pain Index (WPI) and Symptom Severity Scale (SSS), with follow-up DAS28-CRP. Multiple linear regression analyses were performed, adjusting for clinical and demographic variables.In multiple linear regression models, FSQ score was independently associated with elevated DAS28-CRP scores 12 weeks after DMARD initiation (B=0.039, p=0.012). In secondary analyses, the WPI was significantly associated with increased follow up DAS28-CRP scores (B=0.077, p=0.001), while the SSS was not (B=-0.028, p=0.425).Higher levels of fibromyalgia symptoms weakly predicted worse disease activity after treatment. The primary factor that informed the FSQ's prediction of disease activity was the spatial extent of pain, as measured by the WPI.