Zooming in on Barrett oesophagus using narrow-band imaging: an international observer agreement study.
BACKGROUND
Several classifications of mucosal morphology have been proposed in Barrett oesophagus using narrow-band imaging (NBI). We evaluated a simplified classification in which only the regularity of mucosal and vascular patterns were evaluated.


AIM
To assess the inter and intraobserver agreement and the correlation with histology of a simplified NBI classification of mucosal morphology in Barrett oesophagus combining the experience of two referral centres.


METHODS
Two hundred NBI images [57 high-grade intraepithelial neoplasia (HGIN)/early cancer (EC)] were evaluated twice by four NBI-experienced and four nonexperienced endoscopists in the field of NBI. Endoscopists assessed each image for: quality, suspicion for dysplasia, and regularity of mucosal and vascular patterns. Observer agreement was assessed using kappa statistics.


RESULTS
Overall interobserver agreement for the items evaluated was 'moderate' and varied between 0.42 and 0.44. Overall intraobserver agreement was 'moderate' to 'substantial' (kappa 0.60-0.62). There were no significant differences in agreement between expert and nonexpert endoscopists. Endoscopist correctly identified 71% of the images containing HGIN/EC. Of the areas without HGIN/EC, 68% were correctly identified as not suspicious. Again, there were no significant differences between experts and nonexperts.


CONCLUSION
Our proposed, simplified classification for Barrett mucosal morphology has a moderate interobserver and a moderate to substantial intraobserver agreement. The lack of differences in agreements between expert and nonexpert endoscopists suggests a short learning curve. The disappointing rate for correctly indentifying HGIN/EC, questions, however, whether detailed inspection of Barrett oesophagus with NBI can replace histological sampling.