Myeloperoxidase‐ANCA‐Positive and ANCA‐Negative Patients With Granulomatosis With Polyangiitis: Distinct Patient Subsets

Objective To examine the impact of antineutrophil cytoplasmic antibody (ANCA) type and ANCA-associated vasculitis (AAV) diagnosis on demographic features, disease manifestations, and clinical outcomes. We focused on patients that account for the differences between ANCA type and disease type classifications: anti-myeloperoxidase (MPO) ANCA-positive and ANCA-negative patients with granulomatosis with polyangiitis (GPA). Methods Pooled analysis of the Wegener's Granlomatosis Etanercept Trial (WGET) and the Rituximab in AAV (RAVE) trial comparing MPO-ANCA+ GPA and ANCA-negative GPA patients to proteinase 3 (PR3) ANCA+ GPA and MPO-ANCA+ microscopic polyangiitis (MPA) patients. Results Of the 365 patients analyzed, 273 (75%) had PR3-ANCA+ GPA, 33 (9%) had MPO-ANCA+ GPA, 15 (4%) had ANCA-negative GPA, and 44 (12%) had MPO-ANCA+ MPA. MPO-ANCA+ GPA patients were younger at diagnosis compared to MPO-ANCA+ MPA patients (53 versus 61 years, P=0.02). Their disease manifestations and rates of relapse were similar to those of PR3-ANCA+ GPA patients. Relapse was more frequent in MPO-ANCA+ GPA patients than in patients with MPO-ANCA+ MPA at trial entry as well as at 12 and 18 months. ANCA-negative patients with GPA had lower BVAS/WG scores at trial entry than PR3-ANCA+ patients with GPA (4.5 versus 7.7, P<0.01), primarily because of a lower prevalence of renal involvement. Conclusion We were unable to demonstrate important clinical differences between MPO-ANCA+ and PR3-ANCA+ patients with GPA. The risk of relapse was associated more closely with disease type than with ANCA type in this patient cohort. These findings deserve consideration in the assessment of relapse risk in patients with AAV. This article is protected by copyright. All rights reserved.