Combined use of CDAI and blood indices for assessing endoscopic activity in ileocolic Crohn's disease

Mucosal healing has become the primary treatment target for patients with Crohn's disease (CD). We aimed to develop a noninvasive and convenient tool to evaluate the endoscopic activity in patients with ileocolic CD.

A retrospective multicenter study including 300 CD patients (training, 210 patients; test, 90 patients) was conducted at two tertiary referral centers. Independent risk factors associated with endoscopic activity were explored, which were then combined into a comprehensive index. The predictive performance was evaluated with the area under receiver operating characteristic curve (ROC). Cohen's Kappa was adopted to examine the consistency between each indicator and endoscopic activity.

A total of 210 CD patients were recruited in the training cohort. We found that Crohn's Disease Activity Index (CDAI), C-reactive protein (CRP) and platelet-to-lymphocyte percentage ratio (PLpR) were independently associated with endoscopic activity. Additionally, the comprehensive index generated from the above three indices achieved good discrimination and performed better than CDAI in AUC (0.849 vs. 0.769, P < 0.05). This was further well demonstrated by the external test cohort, which showed good discrimination (AUC: 0.84, 95% CI: 0.744-0.936). Intra-individual comparison revealed the comprehensive index to be superior in the prediction of endoscopic activity. In the subgroup analysis, the AUC of comprehensive index was significantly higher than CDAI especially in inflammatory phenotype (0.824 vs. 0.751, P < 0.05).

Combining CDAI, CRP and PLpR significantly improved the accuracy for predicting endoscopic activity in ileocolic CD, which can help better monitor an endoscopic flare.