Objective:To explore the predictive value of serum DcR3 in acute respiratory distress syndrome（ARDS）.Methods:A prospective nested case-control study was conducted and 42 acute respiratory distress syndrome patients were enrolled.Of which

there were 21 non survivors and 21 survivors.The Berlin definition was used as a diagnostic criteria.Sera DcR3 concentrations were tested.Cox regression was used to evaluate the predictive value.Results:Thirty day all-cause mortality was 50% and the mortality was 23.1% for those with mild ARDS

60.9% for those with moderate ARDS

and 66.7% for those with severe ARDS.Baseline sera DcR3 levels were higher in non survivors than survivors（P=0.014）.Sera DcR3 in mild

moderate and severe ARDS were 1.8（1.3 to 2.9）ng/mL

2.4（1.2 to 4.8）ng/mL

4.0（2.9 to 5.5）ng/mL

respectively

P=0.048.Sera DcR3 were higher in non survivors than in survivors[3.1（2.4 to 5.5）ng/mL vs.1.8（1.1 to 2.7）ng/mL

P=0.014].Baseline sera DcR3 in patients developed MODS were higher than those who did not develop MODS[3.6（2.4 to 5.5）ng/mL vs.1.8（1.1 to 2.9）ng/mL

P=0.011]

.Cox regression showed that sera DcR3≥2.7 ng/mL（HR=2.557

95%CI=1.016 to 6.432

P=0.046）

developing MODS（HR=4.667

95%CI=1.751 to 12.443

P=0.020） and PaO

2

/FiO

2

≤165 mm Hg（HR=2.737

95%CI=1.049 to 7.141

P=0.040）were independently associated with an elevated risk of 30 day allcause mortality.Conclusion:Serum DcR3 level is associated with ARDS severity.Patients with higher sera DcR3 were associated with an elevated risk of developing MODS and 30 day all-cause mortality.