Assessment of Treatment Response in Known Crohn's Disease-A Prospective Blinded Study Comparing the Diagnostic Accuracy of Intestinal Ultrasound, Magnetic Resonance Enterocolonography, Panenteric Capsule Endoscopy, and Fecal Calprotectin.

Background: Minimally invasive modalities may replace ileocolonoscopy (IC) in the follow-up of Crohn's disease (CD). The aim of this study was to evaluate intestinal ultrasound (IUS), magnetic resonance enterocolonography (MREC), panenteric capsule endoscopy (PCE), and fecal calprotectin (FC) for determining response to medical treatment in patients with ileocolonic CD.

Methods: This prospective, blinded, multicenter study included patients with endoscopically active CD. Patients were scheduled for IC, MREC, IUS, PCE, and FC before and 12 weeks after treatment with corticosteroids or biological therapy. A ≥50% reduction of the Simple Endoscopic Score for Crohn's Disease (SES-CD) with IC defined treatment response.

Results: Fifty patients completed the pre- and posttreatment evaluation with IC, and endoscopic response was achieved in 25 (50.0%). PCE was omitted in 12 (24.0%) patients because of stricturing CD. All activity scores decreased in patients achieving endoscopic response: The Simple Ultrasound Score for Crohn's Disease 2.2 vs 6.1 (P < .001), Magnetic Resonance Index of Activity 29.0 vs 37.1 (P = .05), SES-CD with PCE 3.1 vs 12.8 (P < .001), and FC 115.3 vs 1339.9 mg/kg (P < .001). The sensitivity and specificity of IUS, MREC, PCE, and FC were 80.0% (95% CI, 56.3-94.3)/77.8% (95% CI, 52.4-93.6), 65.2% (95% CI, 42.7-83.6)/87.0% (95% CI, 66.4-97.2), 87.5% (95% CI, 61.7-98.4)/86.7% (95% CI, 59.5-98.3), and 90.0% (95% CI, 68.3-98.8)/86.4% (95% CI, 65.1-97.1), respectively.

Conclusions: IUS and FC are equally effective for determining treatment response in patients with active CD. PCE is limited by the occurrence of strictures in this group of patients.