Purpose: Currently several different instruments are used to measure disease activity and extent in clinical trials of ANCA-associated vasculitis leading to division among investigative groups and difficulty comparing study results. An exercise comparing 6 different vasculitis instruments was performed.
Methods: Ten experienced vasculitis investigators from 5 countries scored 20 paper cases of Wegener's granulomatosis or microscopic polyangiitis using 6 disease assessment tools: the Birmingham Vasculitis Activity Score (BVAS), The BVAS for Wegener’s granulomatosis (BVAS/WG), BVAS2003, a physician global assessment (PGA), the Disease Extent Index (DEI), and the Five Factor Score (FFS). Five cases were re-scored by all raters.
Results: Reliability of the measures was extremely high: intraclass correlations for the 6 measures all=0.98. Within each instrument, there were no significant differences or outliers among the 10 investigators’ scores. Test/re-test reliability was high for each measure: range=0.77-0.95. The scores of the 5 acute activity measures correlated extremely well with one another.
Conclusions: Currently available tools for measuring disease extent and activity in ANCA-associated vasculitis are highly correlated and reliable. These results provide investigators with confidence to compare different clinical trial data and helps form common ground as international research groups develop new, improved, and universally accepted vasculitis disease assessment instruments.