CHI3L1 and polymyositis: Hozumi et al. also demonstrated a correlation between serum YKL-40 levels and a lower arterial oxygen pressure (r =  − 0.40, P < 0.001) in 72 patients with polymyositis/dermatomyositis-ILD, and independent association with poor prognosis under multivariable Cox analysis when adjusted by the anti-aminoacyl tRNA synthetase status (per 10 ng/ml increase, HR = 1.15, 95% CI 1.04–1.28, P < 0.01) or the anti-CADM-140/melanoma differentiation-associated gene 5 antibody status (per 10 ng/mL increase, HR = 1.15, 95% CI 1.04–1.29, P < 0.01)21.