Rationale of concomitant cyclophosphamide for remission-induction in patients with antineutrophil cytoplasmic antibody-associated vasculitis: A propensity score-matched analysis of two nationwide prospective cohort studies

Objectives: We evaluated the effectiveness of cyclophosphamide for patients with microscopic polyangiitis and granulomatosis with polyangiitis. Methods: Patients treated with cyclophosphamide and glucocorticoid (cyclophosphamide group) or glucocorticoid alone (non-cyclophosphamide group) for remission-induction were enrolled from two Japanese nationwide prospective inception cohort studies. The effectiveness and safety outcomes were compared before and after propensity score (PS)- matching. Results: Proportion of patients achieving Birmingham Vasculitis Activity Score (BVAS)-remission and BVAS-remission plus a daily prednisolone dosage of ≤10 mg (GC-remission) by Month 6 were not significantly different between cyclophosphamide and non-cyclophosphamide groups before (n = 144 and 155) and after (n = 94 for each group) PS-matching. In myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA)-positive PS-matched patients, GC-remission by Month 6 was superior in CYC group (n = 82) than in non-CYC group (n = 91) (49 vs. 31%, p =.020). Overall, end-stage renal disease-free and relapse-free survival rates, Vasculitis Damage Index score, and proportions of serious infection were comparable between the two groups both in the unmatched and PS-matched patients. Prednisolone doses at any point after treatment initiation in the PS-matched patients were lower in the cyclophosphamide group than in a non-cyclophosphamide group. Conclusions: Concomitant cyclophosphamide use may improve GC-remission by Month 6 in MPO-ANCA-positive patients and could exert glucocorticoid sparing effect.