Diagnostic Accuracy of Fecal Calprotectin for the Detection of Small Bowel Crohn's Disease through Capsule Endoscopy: An Updated Meta-analysis and Systematic Review.

Background/aims The diagnosis of small bowel Crohn's disease with negative ileocolonoscopic findings has been challenging. Fecal calprotectin (FC) has been used to detect colonic inflammation, but its efficacy for detecting small bowel inflammation is less established. We performed an updated meta-analysis to evaluate the diagnostic accuracy of FC to detect active small bowel inflammation observed during capsule endoscopy. Methods We conducted a systematic literature search for studies that evaluated the correlation between small bowel inflammation and FC in patients with suspected/established Crohn's disease. We calculated the pooled sensitivity, specificity, and diagnostic odds ratios (DORs) and constructed hierarchical summary receiver operating characteristic curves for FC cutoffs of 50, 100, and 200 µg/g. Results Fourteen studies were eligible for the final analysis. The DORs of all FC cutoffs were significant. The highest DOR was observed at 100 µg/g (sensitivity, 0.73; specificity, 0.73; and DOR, 7.89) and was suggested as the optimal diagnostic cutoff. If we analyzed only studies that included patients with suspected Crohn's disease, the DOR was 8.96. If we analyzed only studies that included patients with a Lewis score ≥135 as a diagnostic criterion for active disease, the DOR was 10.90. Conclusions FC has significant diagnostic accuracy for detecting small bowel inflammation, and an FC cutoff of 100 µg/g can be used as a tool to screen for small bowel Crohn's disease.