Nation-wide cohort study of remission induction therapy using rituximab in Japanese patients with antineutrophil cytoplasmic antibody–associated vasculitis: Effectiveness and safety in the first 6 months

Objectives:The aim of this article is to evaluate the effectiveness and safety of rituximab (RTX) for microscopic polyangiitis and granulomatosis with polyangiitis in Japan. Methods: In this prospective observational study, all patients with microscopic polyangiitis and granulomatosis with polyangiitis administered RTX were enrolled at each institution. During the observation period of 2 years, data up to 6 months were analysed. Cox proportional hazards analysis was used to assess the factors associated with an outcome. Results: Of the 75 patients who received RTX for remission induction therapy, 53 achieved remission by the sixth month and 50 were in remission at the sixth month. During therapy, 38 serious adverse events were observed in 24 patients, 21 serious infections in 16 patients, and 9 patients died. No factors were associated with remission; however, there was a significant difference between patients with and without remission in serious adverse events (22.6% vs. 54.5%), serious infections (11.3% vs. 45.4%), and death (1.9% vs. 36.4%). The hazard ratio (95% confidence interval) for serious infection was 3.49 (1.29–9.74) for patients aged ≥ 75 years and 3.53 (1.31–9.53) for pulmonary complications. Four patients maintained remission for 6 months. Conclusions: The effectiveness and safety of RTX for microscopic polyangiitis and granulomatosis with polyangiitis for up to 6 months was demonstrated.