To the Editor:
We read with interest the article by Coury, et al1 and the accompanying editorial2 recently published in The Journal on the influence of fibromyalgia (FM) in the activity and severity of rheumatoid arthritis (RA). Recently we conducted a similar, although less ambitious study3. We compared the activity of RA, measured by the Disease Activity Score (DAS)28, in a group of Spanish women with RA with and without FM, and we see similar results to those of Coury, et al.
We analyzed 53 women who met the criteria for RA who consecutively visited an outpatient rheumatology unit, 9 of whom also met criteria for FM. No patient had received biological treatment. The 2 groups were comparable in age, disease duration, acute-phase reactants (erythrocyte sedimentation rate and C-reactive protein), and number of swollen joints (Table 1). However, like Coury, et al, we found differences in the number of painful joints, the modified Health Assessment Questionnaire results, and the assessment of disease by the patient. Given the results of the study of Coury, et al and our own, we agree with these authors that the DAS28 overestimates the activity of RA in patients who also have FM, and that it should be used with caution in assessing disease activity and effectiveness of treatment in these patients.