KL-6 estimation among different groups:
The median serum level of KL-6 was 52.3 U/mL (min 32.8; max 62.4 U/mL) in control group, 56.7 U/mL (min 35.8; max 68.5 U/mL) in CTD only group, 72.2 U/mL (min 58.4; max 100.5 U/mL) in mildILD, and 102.7 U/mL (min 76.1; max 180.8 U/mL) in severeILD group. The KL-6 levels were higher in the severeILD, then mildILD group, and lowest in control groups (table 2).