TNFSF13B and irritable bowel syndrome: Although no significant difference was found between the AUC of faecal BAFF as well as calprotectin for distinguishing IBD from IBS, the test performance of BAFF had an advantage over calprotectin and FOBT under the optimal cutoff value of 227.3 pg/ml, which yield a sensitivity of 84%, a specificity of 100%, a PPV of 100%, and a NPV of 64%.