Prospective evaluation of a simplified narrowband imaging scoring system for a differential diagnosis of colorectal lesions.

BACKGROUND

Narrowband imaging (NBI) allows characterization of colorectal polyps during endoscopy; however, this is underutilized by most US physicians. The aim of this study was to assess diagnostic performance of an NBI scoring system, based on the NBI international colorectal endoscopic classification, and determine a threshold score yielding the highest negative predictive value (NPV) in the characterization of colorectal neoplasia.

METHODS

During colonoscopy, colorectal lesions were scored using the NBI scoring system on a 0-3 scale for NBI findings. All lesions were biopsied or endoscopically removed for pathological examinations.

RESULTS

Two hundred and three patients were enrolled, and a total of 156 colorectal lesions were detected in 67 patients. Diagnostic yields under white light mode showed limited diagnostic performance [accuracy 75.6 % (68.9-82.3), sensitivity 69.2 % (58.6-78.3), specificity 84.6 % (73.1-92.0), positive predictive value (PPV) 86.3 % (75.8-92.9), NPV 66.3 % (55.0-76.0)]. Of NBI threshold scores from 1 to 3 for the diagnosis of neoplastic lesion, the score of ≥1 resulted in an accuracy of 88.5 % (83.5-93.5), sensitivity of 97.8 % (91.5-96.6), and specificity of 75.4 % (62.9-84.9), with PPV of 84.8 % (76.1-90.8) and NPV of 96.1 % (85.4-99.3).

CONCLUSIONS

The threshold value of ≥1 in this simplified NBI scoring system yielded the highest sensitivity and NPV for non-adenomatous colorectal polyps. This scoring system is simple to apply and is superior to white light endoscopy.