Disease Activity and Phenotype

Assessment of disease activity was completed at each study visit using the BVAS/WG instrument with active disease defined as a score of ≥1 and a score of 0 reflecting remission (42). Complete remission was defined as a BVAS/WG of 0 with a prednisone dose of 0 mg. Sustained remission was defined as a BVAS/WG of 0 with a prednisone dose of 0 mg for 6 months. A patient was considered to relapse if there was an increase of BVAS/WG of ≥1 after achievement of complete remission. A severe relapse was defined as an increase in BVAS/WG of >3, new major item on BVAS/WG, or if induction therapy was reinitiated per clinician discretion (43).

Organ manifestations were recorded at enrollment and at each study visit with the BVAS/WG. The disease phenotype used for these analyses are based on that present at the time of enrollment. Patients were categorized into 1 or more of 5 groups: granulomatous disease only, any granulomatous disease, any capillaritis, renal involvement, and alveolar hemorrhage. These partially overlapping categories are described in detail elsewhere (35).