Efficacy and safety of leflunomide 10 mg versus 20 mg once daily in patients with active rheumatoid arthritis:: multinational double-blind, randomized trial

Objective. To compare the efficacy and safety profile of two daily maintenance doses of leflunomide, 10 mg and 20 mg, for the treatment of active rheumatoid arthritis (RA). Methods. In this multinational, randomized, double-blind, parallel-group study, 402 RA patients were randomized equally to receive daily doses of 10 mg leflunomide (n = 202; loading dose on day 3, 100 mg) or 20 mg leflunomide (n = 200; loading dose on day 1-3, 100 mg) for 24 weeks. The study was designed to demonstrate non-inferiority of the efficacy of 10 mg compared with 20 mg by calculating 95% confidence intervals for differences in changes in tender joint count (TJC), swollen joint count (SJC) and Health Assessment Questionnaire Disability Index (HAQ DI), comparing these confidence intervals with predefined bounds. Results. In the intent-to-treat population, mean improvements at the end-point in the 10 and 20 mg groups respectively were: TJC, -7.57 and -8.89 (P = 0.061); SJC, -6.38 and -6.96 (P = 0.304); and HAQ DI, 0-0.37 and 0-0.49 (P = 0.095). By American College of Rheumatology (ACR) greater than or equal to20% criteria, response rates were 49.8 and 56.6% respectively (P = 0.1724). Adverse events (AEs) resulting in treatment withdrawal were higher in the 10 mg (15.3%) than in the 20 mg treatment group (12.0%), as were serious adverse events (SAEs): 12.9 vs 10.0%. Conclusions. This study rejected the hypothesis of non-inferiority of 10 mg compared with 20 mg daily maintenance doses of leflunomide. More AEs resulting in treatment discontinuation and SAEs in patients receiving 10 mg leflunomide daily also support a better efficacy profile for the 20 mg daily dose.