Long-term efficacy of leflunomide on disease activity and inhibition of joint damage: retrospective comparison with methotrexate for Japanese rheumatoid arthritis patients

We retrospectively compared treatment impact with leflunomide (LEF) or methotrexate (MTX) on retarding joint damage and clinical symptom including a 28-joint-count Disease Activity Score/erythrocyte sedimentation rate (DAS28-ESR) between two similar groups in patients with rheumatoid arthritis (RA) over an approximately 3-year treatment. One group included 29 patients treated with LEF alone (average dose 16.1 mg/day); the other group included 26 patients treated with MTX (average dose 7.4 mg/week) alone or combined with other disease-modifying antirheumatic drugs. At baseline, mean disease duration was 7.1 and 6.9 years, and mean DAS28-ESR was 5.79 and 5.69, respectively. The average DAS28-ESR improvement of 1.750 (from 5.79 to 4.04) in the LEF-treated group was significantly greater than the effect of 1.007 (from 5.69 to 4.68) seen in the MTX group (P = 0.0455), with the same results being observed on European League Against Rheumatism (EULAR) response criteria. Annual changes observed in Larsen score in total joints were 0.030 in the LEF group and 0.085 in the MTX group: LEF retards joint damage significantly better than MTX (P = 0.003). This inhibitory effect was better in small joints (P = 0.004) than in middle and large joints (P = 0.075). A negative correlation was noticed between improved DAS28-ESR and the progression of joint damage in the LEF group (r = -0.7068, P < 0.0001), whereas there was no correlation in the MTX group (r = -0.0311, P = 0.882). In daily clinical practice, LEF showed significant clinical and radiological improvement compared with the standard MTX regimen in Japan.