The results of ROC analysis revealed that the area under the curve (AUC) of serum elafin was 0.809 (95% CI: 0.699–0.919; SE: 0.056) while discriminating patients with ulcerative colitis from the control group and that the AUC was 0.664 while differentiating patients with Crohn’s disease from the control group (95% CI: 0.504–0.824; SE: 0.082). Here, PI3 is linked to Crohn disease.