A cross-sectional study of the Birmingham Vasculitis Activity Score version 3 in systemic vasculitis

Methods. A total of 238 patients with vasculitis from seven countries in Europe were evaluated at a single time point. Spearman's correlation coefficients were calculated between BVAS v. 3 scores, vasculitis activity index (VAI), physician's global assessment (PGA), the physician's treatment decision, CRP and the vasculitis damage index (VDI) to demonstrate that the BVAS v. 3 measures disease activity. Results. WG (63%), Churg-Strauss syndrome (9%) and microscopic polyangiitis (9%) were the most common diagnoses. The BVAS v. 3 showed convergent validity with the VAI [ = 0.82 (95% CI 0.77, 0.85)], PGA [ = 0.85 (95% CI 0.81, 0.88)] and the physician's treatment decision [ = 0.54 (95% CI 0.44, 0.62)]. There was little or no correlation between BVAS v. 3 and the CRP level [ = 0.18 (95% CI 0.05, 0.30)] or with the VDI [ = -0.10 (95% CI 0.22, 0.03)]. The inter-observer reliability was very high with an intra-class correlation coefficient (ICC) of 0.996 (95% CI 0.990, 0.998) for the total BVAS v. 3 score. Conclusion. The BVAS v. 3 has been evaluated in a large cohort of patients with vasculitis and the important properties of the tool revalidated. This study increases the utility of the BVAS v. 3 in different populations of patients with systemic vasculitis.