Fig. 1.

Serum YKL-40 levels in patients with severe AAV, high FFS, active disease, and ANCA positivity. Serum YKL-40 levels were significantly higher in patients with a severe AAV and b high FFS compared to those without. c Serum YKL-40 was higher in patients with active disease compared to those in remission from the UK samples. d MPO-ANCA (or P-ANCA)-positive AAV patients had significantly higher serum YKL-40 than those with ANCA negative patients. Data are shown as mean ± standard deviation or median (interquartile range), as appropriate. Differences of two continuous variables were compared using the Student’s t-test and Mann-Whitney U test, whereas Kruskal-Wallis test was conducted for comparing two or more variables. AAV, ANCA-associated vasculitis; ANCA, anti-neutrophil cytoplasmic antibody; FFS, Five factor score; MPO, myeloperoxidase; P, perinuclear; PR3, proteinase 3; C, cytoplasmic