A Comparison of Magnifying Chromoendoscopy Versus Narrow Band Imaging in the Diagnosis of Depth of Invasion for Early Colorectal Cancers

Although chromoendoscopy and narrow band imaging (NBI) are widely used in diagnosing the invasion depth of colorectal cancers, comparative studies of these modalities are lacking. This meta-analysis compared the performance of these two modalities in colorectal cancer diagnosis. MEDLINE, EMBASE, and Cochrane Library were searched for relevant original articles published up to December 20th, 2010. Major criteria for article inclusion were: (i) magnifying chromoendoscopy or NBI was used as a diagnostic modality and pit pattern or vascular pattern was used as a diagnostic classification; (ii) sensitivity and specificity were reported; (iii) absolute numbers of true-positive, false-positive, true-negative, and false-negative cases, or their equivalent, were provided; and (iv) pathology of biopsy, endoscopy, or surgical treatment was used as the reference standard. Sensitivity and specificity were pooled using a random effects model. Regression analysis was performed to compare the discriminatory power between chromoendoscopy and NBI by including a dummy variable. We made the assumption that a positive regression coefficient implied a better discriminatory power for NBI, and vice versa. Of 1846 screened articles, 16 fulfilled all inclusion criteria. Pooled sensitivity for chromoendoscopy and NBI was 0.85 (95% CI: 0.82-0.87) and 0.80 (0.76-0.85), respectively, and specificity was 0.98 (0.97-0.99) and 0.98 (0.97-0.99), respectively. The regression coefficient for chromoendoscopy versus NBI was -0.02 (95%CI: -1.18-1.71). These results indicate that chromoendoscopy and NBI may have similar power for the diagnostic assessment of colonic neoplasms. However, other factors such as convenience, time, and cost still must be taken into account in making the final diagnostic choice