Maintenance of Remission and Risk of Relapse in Myeloperoxidase Positive Antineutrophil Cytoplasmic Antibody-Associated Vasculitis with Kidney Involvement

Background.Optimal strategy for remission-maintenance therapy in patients with MPO-ANCA associated vasculitis is not established. Defining parameters to guide maintenance therapy is required.Methods.A retrospective cohort study of all patients with MPO-ANCA associated vasculitis (microscopic with polyangiitis and granulomatosis with polyangiitis) and glomerulonephritis (GN) followed at the Mayo Clinic between 1996-2015. Relapse rate, MPO-ANCA status, and remission-maintenance therapies were reviewed. Logistic regression models, Kaplan Meier method and Cox proportional hazards regression models were applied.Results.We analyzed 159 patients with active MPO-ANCA associated vasculitis with glomerulonephritis. Sixty-six (42%) patients had at least 1 relapse, and 52 (33%) relapsed before 60 months. Patients with MPO-ANCA who became persistently negative did not relapse (HR 0.03, [95%CI, 0.002- 0.431], p=0.01). The reappearance of MPO-ANCA was associated with a higher risk of relapse (HR 1.91, [95%CI, 1.109 - 3.293], p=0.020). Immunosuppression was withdrawn in 80 (50%) patients, and this was less likely in those who received cyclophosphamide for remission-induction or in patients with persistently MPO-ANCA positive (OR 0.44, [95%CI,0.228-0.861], p=0.02; OR 0.42, [95%CI,0.213-0.820], p=0.01, respectively). Relapse frequency was not different between patients with persistently positive MPO-ANCA and patients with MPO-ANCA reappearance (44% vs. 39%, p=0.49) irrespective of remission maintenance treatment. Ear nose an and throat involvement (OR 6.10 [95%CI, 1.280-29.010], p=0.02) and MPO-ANCA reappearance (OR 9.25, [95%CI, 3.126-27.361], p<0.001), were independent associated with relapse after treatment withdrawal.Conclusions.Patients persistently MPO-ANCA negative are at low risk for relapse even without remission maintenance therapy. Persistence or subsequent reappearance of MPO-ANCA is associated with an increased risk of relapse. Serial MPO-ANCA determinations can inform the development of remission-maintenance strategies in patients with MPO-ANCA associated vasculitis with glomerulonephritis.