Values expressed as mean ± standard error or number (percentage). Disease activity and patterns of organ involvement were defined by the BVAS 2003 scoring system. AAV, antineutrophil cytoplasmic antibody-associated vasculitis; BVAS, Birmingham Vasculitis Activity Score; EGPA, eosinophilic granulomatosis with polyangiitis; GPA, granulomatosis with polyangiitis (Wegener’s granulomatosis); MPA, microscopic polyangiitis; RLV, renal-limited vasculitis. Comparisons between the EGPA, GPA, and MPV/RLV groups were made by Student t test or Mann–Whitney U test. Statistical significance was determined by P < 0.05/3 using Bonferroni correction: aEGPA versus GPA, bEGPA versus MPA/RLV, cGPA versus MPA/RLV. Unclassifiable AAV was not compared with other forms of AAV.