Efficacy of Noninvasive Evaluations in Monitoring Inflammatory Bowel Disease Activity: A Prospective Study in China

Aim: To optimize the efficacy of noninvasive evaluations in monitoring the endoscopic activity of inflammatory bowel disease (IBD).

Methods: Fecal calprotectin (FC), clinical activity index (CDAI or CAI), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and procalcitonin (PCT) were measured for 136 IBD patients. Also, FC was measured in 25 irritable bowel syndrome (IBS) patients that served as controls. Then, endoscopic activity was determined by other two endoscopists for colonic or ileo-colonic Crohn's disease (CICD) with the "simple endoscopic score for Crohn's disease" (SES-CD), CD-related surgery patients with the Rutgeerts score, and ulcerative colitis (UC) with the Mayo score. The efficacies of these evaluations to predict the endoscopic disease activity were assessed by Mann-Whitney test, χ test, Spearman's correlation, and multiple linear regression analysis.

Results: The median FC levels in CD, UC, and IBS patients were 449.6 (IQR, 137.9-1344.8), 497.9 (IQR, 131.7-118.0), and 9.9 (IQR, 049.7) μg/g, respectively (P < 0.001). For FC, CDAI or CAI, CRP, and ESR differed significantly between endoscopic active and remission in CICD and UC patients, but not in CD-related surgery patients. The SES-CD correlated closely with levels of FC ( = 0.802), followed by CDAI ( = 0.734), CRP ( = 0.658), and ESR ( = 0.557). The Mayo score also correlated significantly with FC ( = 0.837), CAI (r = 0.776), ESR ( = 0.644), and CRP ( = 0.634). For FC, a cut-off value of 250 μg/g indicated endoscopic active inflammation with accuracies of 87.5%, 60%, and 91.1%, respectively, for CICD, CD-related surgery, and UC patients. Moreover, clinical FC activity (CFA) calculated as 0.8 × FC + 4.6 × CDAI showed higher area under the curve (AUC) of 0.962 for CICD and CFA calculated as 0.2 × FC + 50 × CAI showed higher AUC (0.980) for UC patients than the FC. Also, the diagnostic accuracy of FC in identifying patients with mucosal inflammation in clinical remission was reflected by an AUC of 0.91 for CICD and 0.96 for UC patients.

Conclusion: FC is the most promising noninvasive evaluation for monitoring the endoscopic activity of CICD and UC. CFA might be more accurate for IBD activity evaluation.