Comparative Effectiveness of Rituximab‐ Versus Cyclophosphamide‐Based Remission Induction Strategies in Antineutrophil Cytoplasmic Antibody–Associated Vasculitis for the Risk of Kidney Failure and Mortality

Objective To compare rituximab‐ versus cyclophosphamide‐based remission induction strategies for the long‐term risks of kidney failure and death in antineutrophil cytoplasmic antibody (ANCA)–associated vasculitis (AAV) in a real‐world cohort. Methods We performed a cohort study using the Mass General Brigham AAV Cohort, which includes proteinase 3–ANCA+ and myeloperoxidase (MPO)‐ANCA+ AAV patients diagnosed from January 1, 2002 to December 31, 2019. We included cases in which the initial remission induction strategy was based either on rituximab or cyclophosphamide. The primary outcome was the composite outcome of kidney failure or death. We used multivariable Cox proportional hazards models and propensity score–matched analyses to assess the association of rituximab‐ versus cyclophosphamide‐based treatment strategies with the composite outcome of kidney failure or death. Results Of 595 included patients, 352 patients (~60%) received rituximab‐based and 243 patients (~40%) received cyclophosphamide‐based regimens. The mean age was 61 years, 58% of patients were female, 70% of patients were MPO‐ANCA+, and 69% of patients had renal involvement (median estimated glomerular filtration rate 37.3 ml/minute/1.73 m 2 ). There were 133 events at 5 years, and the incidence rates in rituximab‐ and cyclophosphamide‐based regimens were 6.8 and 6.1 per 100 person‐years, respectively. The risk of kidney failure or death was similar in both groups in multivariable‐adjusted analyses (hazard ratio [HR] 1.03 [95% confidence interval (95% CI) 0.55–1.93]) and in propensity score–matched analyses (HR 1.05 [95% CI 0.55–1.99]) at 5 years. Our findings were similar when outcomes were assessed at 1 and 2 years as well as in subgroups stratified according to renal involvement and severity as well as major organ involvement. Conclusion Rituximab‐ and cyclophosphamide‐based remission induction strategies for AAV are associated with similar risks of kidney failure and death.