Treatment of early seropositive rheumatoid arthritis: Doxycycline plus methotrexate versus methotrexate alone

Abstract

Objective To compare the efficacy of doxycycline plus methotrexate (MTX) versus MTX alone in the treatment of early seropositive rheumatoid arthritis (RA), and to attempt to differentiate the antibacterial and antimetalloproteinase effects of doxycycline. Methods Sixty‐six patients with seropositive RA of P = 0.02). Trend analysis revealed that the ACR20 response and the ACR50 response were significantly different between groups (P = 0.04 and P = 0.03, respectively). MTX doses at 2 years were not different among groups. Four patients in the high‐dose doxycycline group, 2 patients in the low‐dose doxycycline group, and 2 patients in the placebo group were withdrawn because of toxic reactions. Conclusion In patients with early seropositive RA, initial therapy with MTX plus doxycycline was superior (based on an ACR50 response) to treatment with MTX alone. The therapeutic responses to low‐dose and high‐dose doxycycline were similar, suggesting that the antimetalloproteinase effects were more important than the antibacterial effects. Further studies to evaluate the mechanism of action of tetracyclines in RA are indicated.