The effect on treatment response of fibromyalgia symptoms in early rheumatoid arthritis patients: results from the ESPOIR cohort
Duran Santa Cruz, Josefina Gracia
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Rheumatoid arthritis (RA) is a systemic chronic inflammatory disease that can lead to important functional impairment. Although improvements in treatment have been made, still there are a high proportion of patients in whom response to treatment is not complete. Fibromyalgia (FM) is a condition characterized by bodily pain that often coexists with RA. Cross-sectional studies have shown that patients with RA and FM symptoms, or fibromyalgic RA (FRA), have higher disease activity scores than patients with RA and no FRA. Concern has been raised regarding the validity of RA disease activity scores in patients with coexistent RA and FM. In this prospective study, we hypothesized that patients with FRA have an impaired response to treatment measured by traditionally used scores. The present analysis used a study sample obtained from the ESPOIR French cohort. This is a longitudinal prospective cohort of adults with early RA. Patients with RA were classified in two groups according to the presence of FRA. RA disease activity scores (DAS28, SDAI, CDAI and HAQ) were compared as a measure of response to treatment at 6, 12 and 18 months. Results showed that after adjusting for confounders, patients with FRA (120) had higher activity scores than patients with RA and no fibromyalgic characteristics (548). DAS28 and other disease activity scores started out higher in subjects with FRA and while they improved to a similar extent as in the isolated RA group, they remained consistently higher among FRA patients. Achievement of low disease activity and of remission according to established activity score cut-points was significantly less likely in subjects with FRA. In conclusion, patients with FRA and RA had a similar response to treatment according the decrease in indexes of disease activity but more frequently missed the target of remission or low disease activity. These findings may have implications in RA treatment in patients with FRA, as therapy is escalated not in relation to change in scores but to achieving remission.