Azathioprine vs methotrexate in eosinophilic granulomatosis with polyangiitis: a monocentric retrospective study

Objectives To analyse the effectiveness, safety and steroid-sparing effect of AZA and MTX as induction of remission and maintenance treatment in eosinophilic granulomatosis with polyangiitis. Methods We retrospectively collected data from 57 patients divided into four groups according to treatment: MTX/AZA as first-line agents (MTX1/AZA1) in non-severe disease or as second-line maintenance therapy (MTX2/AZA2) in severe disease previously treated with CYC/rituximab. During the first 5 years of treatment with AZA/MTX we compared the groups according to: remission rate [defined as R1: BVAS = 0; R2: BVAS = 0 with prednisone & LE;5 mg/day; R3 (MIRRA definition): BVAS = 0 with prednisone & LE;3.75 mg/day], persistence on therapy, cumulative glucocorticoid (GC) dose, relapse and adverse events (AEs). Results There were no significant differences in remission rates (R1) in each group (63% in MTX1 vs 75% in AZA1, P = 0.53; 91% in MTX2 vs 71% in AZA2, P = 0.23). MTX1 allowed R2 more frequently in the first 6 months compared with AZA1 (54% vs 12%, P = 0.04); no patients receiving AZA1 achieved R3 up to the first 18 months (vs 35% in MTX1, P = 0.07). The cumulative GC dose was lower for MTX2 vs AZA2 (6 g vs 10.7 g at 5 years, P = 0.03). MTX caused more AEs compared with AZA (66% vs 30%, P = 0.004), without affecting the suspension rate. No differences emerged in time-to-first relapse, although fewer patients treated with AZA2 had asthma/ENT relapses (23% vs 64%, P = 0.04). Conclusion A significant proportion of patients achieved remission with both MTX and AZA. MTX1 had an earlier remission on a lower GC dose but MTX2 had a better steroid-sparing effect.