Issues in trial design for ANCA-associated and large-vessel vasculitis.

Randomized clinical trials (RCTs) have informed the management of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis, although challenges still exist. The evidence base for treating large-vessel vasculitis (LVV) is weaker, but initiatives to standardize diagnostic criteria and outcome measures, and to validate biomarkers in LVV, together with newly initiated RCTs should start to address this need. In this Perspectives, we discuss the prerequisites for RCTs in vasculitis, existing trial evidence, continuing unmet needs, potential therapeutic avenues to explore and considerations in the design of future trials.