The area under the curve (AUC) of PCT and WBC count were compared using DeLong’s test: the AUCs of PCT vs. CRP for the detection of the IBD–CDI group and the control group was 0.826 [95% confidence interval (CI) 0.743–0.909] vs. 0.663 [95% confidence interval (CI) 0.551–0.774] (p < 0.05), respectively. This evidence concerns the gene CALCA and inflammatory bowel disease.