ANCA-associated vasculitis — clinical utility of using ANCA specificity to classify patients

Anti-neutrophil cytoplasmic antibodies (ANCAs) specific for leukocyte proteinase 3 and myeloperoxidase — PR3-ANCAs and MPO-ANCAs, respectively — define distinct conditions among patients with ANCA-associated vasculitides (AAV)Classification of patients with small-vessel vasculitis based on ANCA specificity is feasible and could provide timely and clinically relevant diagnostic information more readily than clinical syndromes based on current classification systemsPatients with PR3-AAV and MPO-AAV do not share the same genetic background and have only some pathophysiologic mechanisms in commonANCA specificity predicts response to induction therapies: rituximab is more effective than cyclophosphamide in patients with PR3-AAV (by contrast, both treatments are similarly effective in patients with MPO-AAV)ANCA specificity predicts differences in long-term prognosis: patients with PR3-ANCAs are at higher risk of relapse than patients with MPO-ANCAsFuture studies should evaluate whether the duration of immunosuppressive maintenance therapy should be different for patients with PR3-AAV versus those with MPO-AAV after remission induction