Induction failure in granulomatosis with polyangiitis: a nationwide case-control study of risk factors and outcomes

Abstract Objective To identify characteristics of granulomatosis with polyangiitis (GPA) associated with induction failure, describe salvage therapies and their efficacy. Methods We conducted a nationwide retrospective case-control study of GPA with induction failure between 2006 and 2021. Each patient with induction failure was randomly paired to three controls matched for age, sex and induction treatment. Results We included 51 patients with GPA and induction failure (29 men and 22 women). At induction therapy, median age was 49 years. Twenty-seven patients received intravenous cyclophosphamide (ivCYC) and 24 rituximab (RTX) as induction therapy. Patients with ivCYC induction failure more frequently had PR3-ANCA (93% vs 70%, P = 0.02), relapsing disease (41% vs 7%, P