Diagnostic accuracy of narrow-band imaging and pit pattern analysis significantly improved for less-experienced endoscopists after an expanded training program

Background: Previous reports assessing diagnostic skill using narrow-band imaging (NBI) and pit pattern analysis for colorectal polyps involved only highly experienced endoscopists. Objective: To evaluate diagnostic skills of less-experienced endoscopists (LEE group) for differentiation of diminutive colorectal polyps by using NBI and pit pattern analysis with and without magnification after an expanded training program. Design: Prospective study. Patients: This study involved 32 patients with 44 colorectal polyps (27 adenomas and 17 hyperplastic polyps) of ≤5 mm that were identified and analyzed by using conventional colonoscopy as well as non-magnification and magnification NBI and chromoendoscopy followed by endoscopic removal for histopathological analysis. Intervention: Before a training course, 220 endoscopic images were distributed in randomized order to residents with no prior endoscopy experience (NEE group) and to the LEE group, who had performed colonoscopies for more than 5 years but had never used NBI. The 220 images were also distributed to highly experienced endoscopists (HEE group) who had routinely used NBI for more than 5 years. The images were distributed to the NEE and LEE groups again after a training class. Magnification NBI and chromoendoscopy images were assessed by using the Sano and Kudo classification systems, respectively. Main outcome measurements: Diagnostic accuracy and interobserver agreement for each endoscopic modality in each group. Results: Diagnostic accuracy was significantly higher, and kappa (κ) values improved in the LEE group for NBI with high magnification after expanded training. Diagnostic accuracy and κ values when using high-magnification NBI were highest among endoscopic techniques for the LEE group after such training and the HEE group (accuracy 90% vs 93%; κ = 0.79 vs 0.85, respectively). Limitations: Study involved only polyps of ≤5 mm. Conclusion: Using high-magnification NBI increased the differential diagnostic skill of the LEE group after expanded training so that it was equivalent to that of the HEE group.