Utility of confocal laser endomicroscopy in identifying high-grade dysplasia and adenocarcinoma in Barrett's esophagus: a systematic review and meta-analysis.

Confocal laser endomicroscopy (CLE) is a novel endoscopic technique that has emerged as an important tool in the in-vivo visualization and detailed assessment of the mucosal layer and subcellular structures in Barrett's esophagus. Current guidelines recommend four-quadrant random biopsies for identification of high-grade dysplasia (HGD) in Barrett's esophagus. However, random biopsies are associated with sampling error and inconsistent histopathologic interpretation. CLE, by providing targeted biopsies, could decrease the sampling error and increase the yield of detection of HGD/adenocarcinoma [esophageal adenocarcinoma (EAC)]. We carried out a meta-analysis to evaluate the diagnostic accuracy of the CLE-based targeted biopsies in detecting HGD/adenocarcinoma compared with four-quadrant random biopsies. A search using medical subject headings (MeSH) terms and keywords was performed in the MEDLINE and Cochrane review databases and relevant studies were identified. All the studies that compared the diagnostic yield from CLE-based targeted biopsies to detect HGD/adenocarcinoma with a gold standard of histopathology were included and a meta-analysis was carried out to estimate the pooled sensitivity, specificity, and positive and negative likelihood ratios using Meta-Disc software. There were a total of seven studies with 345 patients and 3080 lesions that were finally included in the meta-analysis. All the studies had reported per-lesion analyses; however, only four of the seven studies had data reported on per-patient analyses. 'Per-lesion' analysis for the diagnosis of HGD/adenocarcinoma yielded a pooled sensitivity and specificity of 68% [95% confidence interval (CI) of 64-73%] and 88% (95% CI of 87-89%), respectively. The pooled positive and negative likelihood ratios were 6.56 (95% CI of 3.61-11.90) and 0.24 (95% CI of 0.09-0.63), respectively. Similar numbers were calculated on the basis of 'per-patient' basis, which showed a pooled sensitivity and specificity of 86% (95% CI of 74-96%) and 83% (95% CI of 77-88%), respectively. The pooled positive and negative likelihood ratios were 5.61 (95% CI of 2.00-15.69) and 0.21 (95% CI of 0.08-0.59), respectively. CLE, by providing targeted biopsies, has a good diagnostic accuracy in identifying HGD/EAC; however, the overall prevalence of HGD/EAC in the studies included was much higher than what would be seen in clinical practice and these results should be interpreted with caution. Because of its relatively low sensitivity and negative predictive value, CLE may currently not replace standard biopsy techniques for the diagnosis of HGD/EAC in Barrett's esophagus.