Classification of ANCA-associated vasculitis.

Classification of the ANCA-associated vasculitides remains controversial. Existing systems, developed by the American College of Rheumatology (ACR) in 1990, the Chapel Hill Consensus Conference (CHCC) in 1994 and updated in 2012, and the European Medicines Agency algorithm, all have deficiencies, especially when applied to unselected patients. The ACR system did not include ANCA or microscopic polyangiitis, and the CHCC (1994) included MPA but not ANCA (this was rectified in the 2012 revision). These systems were developed as classification criteria and not as diagnostic criteria. There are currently no validated diagnostic criteria for AAV. The Diagnostic and Classification Criteria for Vasculitis (DCVAS) study is a global study with the objective of developing and validating diagnostic criteria.