Figure 1. The level of 25(OH)D in the healthy control, IPF and CTD-ILD. (A) The mean level of 25(OH)D was 16.06±4.33 ng/ml in the CTD-ILD group, 25.18±7.43 ng/ml in the IPF group and 27.33±5.30 ng/ml in the control group. The serum 25(OH)D levels were obviously lower in patients with CTD-ILD compared with the IPF group (P < 0.05) and the control group (P < 0.05). (B) The CTD-ILD groups were divided into two subgroups: anti-MDA5 antibody-positive and anti-MDA5 antibody-negative groups. A statistically significant difference in vitamin D levels was found in the two subgroups(P=0.006).