Efficacy and safety of leflunomide and predisposing factors for treatment response in patients with active rheumatoid arthritis: RELIEF 6-month data.

Objective: The RELIEF investigation was a 48-week, multicenter, international study comprising 2 phases. Results from the first phase, a 24-week open-label cohort study that evaluated the safety and efficacy of leflunomide, as well as predisposing factors to treatment response, are reported here.

Methods: Patients received leflunomide 100 mg once daily for 3 days, followed by 20 mg once daily thereafter. All adverse events were documented. Efficacy variables were the European League Against Rheumatism (EULAR) response criteria using the Disease Activity Score (DAS 28) responder rate and the response rate according to American College of Rheumatology (ACR) criteria. At Week 24, baseline data were analyzed to determine predictive factors for treatment response.

Results: A total of 969 patients were entered in the trial. No adverse events that have not previously been seen with leflunomide were reported. Among 968 evaluable patients, 673 (69.6%) completed 24 weeks of treatment and were responders according to DAS 28 response rate, and 587 (60.6%) completed 24 weeks of treatment and were responders according to ACR 20%. Thus, there was a high correlation between the EULAR and ACR criteria in determining treatment response. In addition, 240 (24.8%) patients had a low DAS 28 (< or = 3.2) and 123 (12.7%) patients fulfilled the disease remission criteria (DAS 28 < 2.6) at the end of the study.

Conclusion: This study demonstrates that leflunomide is well tolerated, with a safety profile similar to that seen previously in Phase III studies, and confirms the efficacy of leflunomide across a range of patient categories.