Comparison of methotrexate and azathioprine as the first-line steroid-sparing immunosuppressive agents in patients with Takayasu ' s arteritis

Background: Immunosuppressive (IS) agents are recommended for the first -line treatment of patients with active Takayasu 's arteritis (TAK) together with glucocorticoids (GCs). However, there is limited data comparing the efficacy and outcomes of different IS agents for this purpose. Objectives: In this study, we aimed to compare the outcomes of two most frequently used first -line IS agents, namely methotrexate (MTX) and azathioprine (AZA) in TAK patients. Methods: TAK patients who received any IS agent in addition to GCs as the initial therapy were included in this multicentre, retrospective cohort study. Clinical, laboratory and imaging data of the patients were assessed. In addition, a matched analysis (cc match) using variables 'age ', 'gender ' and 'diffuse aortic involvement ' was performed between patients who received MTX or AZA as the first -line IS treatment. Results: We recruited 301 patients (F/M: 260/41, mean age: 42.2 +/- 13.3 years) from 10 tertiary centres. As the first -line IS agent, 204 (67.8 %) patients received MTX, and 77 (25.6 %) received AZA. Less frequently used IS agents included cyclophosphamide in 17 (5.6 %), leflunomide in 2 (0.5 %) and mycophenolate mofetil in one patient. The remission, relapse, radiographic progression and adverse effect rates were similar between patients who received MTX and AZA as the first -line IS agent. Vascular surgery rate was significantly higher in the AZA group (23% vs. 9 %, p = 0.001), whereas the frequency of patients receiving <= 5 mg/day GCs at the end of the follow-up was significantly higher in the MTX group (76% vs 62 %, p = 0.034). Similarly, the rate of vascular surgery was higher in AZA group in matched analysis. Drug survival was similar between MTX and AZA groups (median 48 months, MTX vs AZA: 32% vs 42 %, p = 0.34). IS therapy was discontinued in 18 (12 MTX, 6 AZA) patients during the follow-up period due to remission. Among those patients, two patients had a relapse at 2 and 6 months, while 16 patients were still on remission at the end of a mean 69.4 ( +/- 50.9) months of follow-up. Conclusions: Remission, relapse, radiographic progression and drug survival rates of AZA and MTX were similar for patients with TAK receiving an IS agent as the first -line f therapy. The rate of vascular surgery was higher and the rate of GC dose reduction was lower with AZA compared to MTX at the end of the follow-up.