BVAS version 3 and BVAS/GPA: standing on the same line?

Introduction/objectives: Birmingham vasculitis activity score (BVAS) version 3 (BVAS 3.0) and BVAS/granulomatosis with polyangiitis (BVAS/GPA) are used as indicators of disease activity in anti-neutrophil cytoplasmic antibody-associated vasculitis. We evaluated the association between these indices and the significance in patients with GPA and microscopic polyangiitis (GPA/MPA). Methods: We retrospectively reviewed the records of 203 patients with GPA/MPA in our hospital. The correlation between BVAS 3.0 and BVAS/GPA with the five-factor score (FFS) and laboratory data was investigated. The episodes of all-cause mortality, end-stage renal disease, and disease relapse were counted as adverse clinical outcomes. Multivariate Cox hazard analyses were performed to assess the relationships between both indices and patient outcomes. Results: Sixty-five (32.0%) and 138 (68.0%) patients with GPA and MPA were included. The median BVAS 3.0 was significantly higher in patients with MPA than in those with GPA (13.0 vs. 11.0, p = 0.015), whereas BVAS/GPA was higher in patients with GPA (4.0 vs. 3.0, p = 0.001). BVAS 3.0 and BVAS/GPA correlated significantly (r = 0.670, p < 0.001); both BVAS 3.0 and BVAS/GPA were shown to be associated with the outcomes investigated in separate Cox models. However, the correlation between BVAS 3.0 and BVAS/GPA was especially higher in a subgroup of patients with MPA than in those with GPA (MPA: r = 0.817, p < 0.001 vs. GPA: r = 0.570, p < 0.001) and with renal involvement (r = 0.676, p < 0.001). Conclusions: Although both BVAS 3.0 and BVAS/GPA significantly correlated and predicted outcomes well in those with GPA/MPA, a discord was observed based on disease subtypes and organ involvement.Key Points• BVAS 3.0 and BVAS/GPA significantly correlated and predicted outcomes in those with GPA/MPA.• A discordance was also observed based on disease subtypes and organ involvement.