A disease-specific activity index for Wegener's granulomatosis - Modification of the Birmingham Vasculitis Activity Score

Objective. To refine and validate the Birmingham Vasculitis Activity Score (BVAS) as a disease-specific activity index for Wegener's granulomatosis (W G). Methods. Sixteen members of the International Network for the Study of the Systemic Vasculitides (INSSYS) revised the BVAS, with 3 goals: to reduce th e redundancy of some component items, to enhance its ability to capture imp ortant disease manifestations specific to WG, and to streamline the instrum ent for use in clinical research. We defined the items and weighted them em pirically as either minor (e.g., nasal crusting = 1 point) or major (e.g., alveolar hemorrhage = 3 points). We then validated the new, disease-specifi c BVAS/WG in 2 simulation exercises and a clinical case series that involve d 117 patients with WG. Results. We removed 38 items from the original BVAS, revised 9 items, and a dded 7 new items. Correlations between the scores on the BVAS/WG and the ph ysician's global assessment (PGA) of disease activity were high. even when patients in remission were excluded. In the clinical case series, Spearman' s rank correlation coefficient between the BVAS/WG and the PGA was r = 0.81 (95% confidence interval 0.73-0.87). The interobserver reliability using i ntraclass (within-case) correlation coefficients in the 2 simulation exerci ses was r = 0.93 for the BVAS/WG and r = 0.88 for the PGA in the first and r = 0.91 for the BVAS/WG and r = 0.88 for the PGA in the second. There was no significant observer effect in the scoring of the BVAS/WG or the PGA. Th e discriminant validity of the BVAS/WG was good: r = 0.73 (95% confidence i nterval 0.43-0.83). Conclusion. The BVAS/WG is a valid, disease-specific activity index for WG. Tested in simulation exercises and in actual patients, the BVAS/WG correla tes well with the PGA, is sensitive to change, and has good inter- and intr aobserver reliability. The INSSYS will use the BVAS/WG to assess the primar y outcome in a phase II/III trial of etanercept in WG.