Ultrasound as a diagnostic tool in detecting active Crohn's disease: a meta-analysis of prospective studies

Objectives To evaluate the diagnostic accuracy of ultrasound in assessing active Crohn's disease (CD) in adults. Methods We systematically searched PubMed, EMBASE, Web of Science and the Cochrane Library for prospective studies in which ultrasound was performed to evaluate active CD in adults from January 1993 to April 2013. Pooled sensitivity, specificity, positive and negative likelihood ratios (LR+ and LR-) and diagnostic odds ratios (DORs) in a perpatient- based analysis were estimated. Additionally, the area under the receiver-operating characteristic (ROC) curve was calculated to measure the diagnostic accuracy of ultrasound in patients with known or suspected CD. Results Fifteen studies involving 1,558 patients were included in this meta-analysis. Overall, the pooled sensitivity (0.88) and LR-(0.14) were not heterogeneous, whereas the pooled specificity (0.97, I-2=72.9 %) and LR+(15.10, I-2=71.8 %) were. The DOR of ultrasound for assessing active CD was 121.70, with significant heterogeneity (I-2=63.3 %). A symmetrical summary ROC curve was plotted showing that the area under the curve was 0.94, indicating good diagnostic accuracy. Meta-regression and subgroup analysis showed that the disease location may be a major cause of heterogeneity. Conclusions This meta-analysis suggests that ultrasound has high diagnostic accuracy in detecting active CD in adults, especially for small bowel CD. Key Points Ultrasound can detect active Crohn's disease (CD). A meta-analysis of ultrasound for detecting active CD was carried out. This revealed that ultrasound has high diagnostic accuracy for detecting CD.