Fibromyalgia with elevated rheumatoid factor is associated with poor therapeutic response but not with progression to rheumatoid arthritis. Prospective cohort study.

Objetive: Evaluate response to treatment and progression to rheumatoid arthritis (RA) in patients with fibromyalgia (FM) associated with elevated rheumatoid factor (RF).

Material And Methods: Prospective cohort study. The sample consisted of 124 patients with FM: 62 with high RF (>20 U/mL) and 62 with negative RF (0-20 U/mL).