Background The basic theme of AAV is relapse and remission. The maintenance therapy of AAV aimed to reduce or prevent relapse is very challenge. Although many medications have been used for the maintenance of AAV, Leflunomide (LEF) has not studied thoroughly yet. So far, only one study tested the efficacy of LEF in the maintenance therapy for AAV. However, the sample size of this study is small, so large size clinical study is needed to clarify the role of LEF in the maintenance of AAV.~LEF is one of the most frequently prescribed DMARDs in the treatment of rheumatic diseases in China. It is cheap and widely available. Many experiences have been accumulated about its efficacy and safety in Chinese patients with rheumatic diseases. But there is no study to show its effectiveness in the reduction of the relapse of AAV in China. In this study, we try to compare the effectiveness of LEF and AZA, the gold standard for maintenance therapy, in the maintenance of AAV.~Objectives To verify that the effectiveness of LEF in reducing relapse is not inferior to AZA by comparing the relapse rate of LEF and AZA during the 18 month maintenance treatment of AAV.~Study Design This is a prospective, randomized, open-label, control, non-inferiority study.
This study is a prospective, open-labelled, randomized, controlled,multi-center clincial trial. The aim of this study is to verify that the remission rate of patients treated with Leflunomide is not inferior to that of patients treated with Azathioprine.