Background/aims: Narrow band imaging (NBI) endoscopy can be used for gross differentiation between the types of colonic polyps. This study was conducted as a retrospective study for estimation of the interobserver and intra-observer agreement of the pit pattern of the mucosal surface and the accuracy of histology prediction.
Methods: A total of 159 patients underwent complete colonoscopy and 219 polyps examined by NBI endoscopy without magnification were assessed. Interobserver and intra-observer agreement were calculated by investigators in each group for determination of the surface pattern and prediction of histology based on the modified Kudo's classification using intraclass correlation coefficient.
Results: Interobserver agreement for the surface pit pattern and prediction of polyp type was 0.84 and 0.73 in experienced endoscopists, and 0.86 and 0.62 in trainees, respectively. Intra-observer agreement for the surface pit patterns and prediction of polyp type was 0.81, 0.83, 0.85, 0.83, 0.56, 0.84, 0.51, 0.83, and 0.71; and 0.71, 0.70, 0.82, 0.54, 0.72, 0.37, 0.51, 0.34, and 0.30, respectively. The diagnostic accuracy for prediction of polyp type was 69.4% for experienced endoscopists and 72.9% for trainees.
Conclusions: NBI endoscopy without magnification showed fairly good inter and intra-observer agreement for the pit pattern of the mucosal surface and the accuracy of histology prediction; however, it had some limitation for differentiation of colon polyp histologic type. Training and experience with NBI is needed for improvement of accuracy.