CHI3L1 and rheumatoid arthritis: Compared with RA-nILD (median [IQR], 32.19 [21.63-56.99] ng/mL), the serum CHI3L1 levels were increased in RA-ILD patients (median [IQR], 69.69 [44.51-128.66] ng/ml, p<0.001).