Granulomatosis With Polyangiitis and Microscopic Polyangiitis: A Systematic Review and Meta‐Analysis of Benefits and Harms of Common Treatments

OBJECTIVE: The aim of this systemic review is to compare different treatments for patients with granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) to inform evidence‐based recommendations for the American College of Rheumatology (ACR)/Vasculitis Foundation (VF) Vasculitis Management Guidelines. METHODS: A systemic review was conducted by searching articles in English using OVID Medline, PubMed, Embase, and the Cochrane Library. Articles were screened for suitability in addressing PICO questions, with studies presenting the highest level of evidence given preference. RESULTS: A total of 729 full‐text articles addressing GPA and MPA PICO questions were reviewed. For remission induction, rituximab was shown to be noninferior to cyclophosphamide (CYC) (odds ratio [OR]: 1.55, moderate certainty of evidence). The addition of plasma exchange to induction therapy in severe disease did not improve the composite end point of death or end stage renal disease (hazard ratio [HR]: 0.86 [95% confidence interval CI: 0.65, 1.13], moderate certainty of evidence). In nonsevere disease, methotrexate was noninferior to CYC for induction of remission (remission at 6 months of 90% vs. 94%). For maintenance of remission, methotrexate and azathioprine showed no difference in the risk of relapse over a mean follow‐up of 29 months (HR: 0.92, [95% CI: 0.52, 1.65]low certainty of evidence). As maintenance therapy, rituximab was superior to a tapering azathioprine strategy in major relapse‐free survival at 28 months (HR: 6.61, [95% CI: 1.56, 27.96], moderate certainty of evidence). In two randomized trials, longer‐term azathioprine maintenance therapy (>24 months) is associated with fewer relapses without an increase in adverse events. CONCLUSION: This comprehensive systematic review synthesizes and evaluates the benefits and toxicities of different treatment options for GPA and MPA.