Fig. 3.

Serum YKL-40 levels in patients with AAV, SLE, RA, OA, and HC. Patients with AAV exhibited significantly higher serum YKL-40 levels compared to those with SLE, RA, OA, and HC. Data are shown as mean ± standard deviation or median (interquartile range), as appropriate. Differences of two continuous variables were compared using the 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; SLE, systemic lupus erythematosus; RA, rheumatoid arthritis; OA, osteoarthritis; HC, healthy control