Classification of vasculitis: From historical controversies to present day pragmatic consensus

The classification of the systemic vasculitides has been controversial for several decades. However, over the past twenty years there have been several major developments, which means that there is pragmatic consensus regarding classification. These include the American College of Rheumatology criteria first published in 1990, and the Chapel Hill Consensus Conference definitions originally promulgated in 1994, but revised and extended in 2012. More recently the classical division of the ANCA vasculitides using clinical phenotype has come under scrutiny with evidence from epidemiological, genetic and outcome studies that perhaps these conditions should be classified on the basis of ANCA specificity into PR3-ANCA positive and MPO-ANCA positive groups. There remains, however, a major need for validated classification and diagnostic criteria, a need which hopefully the DCVAS project will address.