Background: there are no clarified non-invasive methods to evaluate small bowel inflammation in Crohn's disease.
Aims: to evaluate the accuracy of fecal calprotectin and capsule endoscopy for the diagnosis of small bowel Crohn's disease and to predict relapse.
Methods: a systematic literature search was performed for studies to diagnose and predict relapse of the disease with fecal calprotectin and capsule endoscopy. The relevant pooled data including sensitivity, specificity, diagnostic odds ratio, positive likelihood ratio, negative likelihood ratio and area under curve were calculated using Stata 14.0.
Results: twenty-one studies were included in the final analyses. The diagnostic accuracy of the disease and relapse were obtained for capsule endoscopy, with a pooled sensitivity of 0.90 and 0.82, specificity of 0.76 and 0.56, diagnostic odds ratio of 33 and 6, and area under curve of 0.92 and 0.82, respectively. Diagnostic accuracy of the disease was calculated for fecal calprotectin values of 50, 100 and 200 ug/g; the sensitivity values were 0.84, 0.66 and 0.45; specificity values were 0.49, 0.74 and 0.87; diagnostic odds ratio were 5, 5 and 5; and area under curve were 0.74, 0.76 and 0.75, respectively. A fecal calprotectin level of 100-140 ug/g for the prediction of relapse had a pooled sensitivity of 0.68, specificity of 0.91, diagnostic odds ratio of 21, and area under curve of 0.77.
Conclusion: capsule endoscopy is effective in diagnosing small bowel Crohn's disease and predicting relapse. Fecal calprotectin is an accurate surrogate technique to diagnose small bowel inflammation in Crohn's disease. Furthermore, the best scenario for fecal calprotectin is the prediction of relapse.