Accurate optical characterization and removal of small adenomas (<10 mm) at colonoscopy would allow hyperplastic polyps to be left in situ and surveillance intervals to be determined without the need for histopathology.
Although accurate in specialist practice the performance of narrow band imaging, colonoscopy in routine clinical practice is poorly understood.
Professor Colin Rees and colleagues from the United Kingdom compared narrow band imaging-assisted optical diagnosis with reference standard histopathological findings in a prospective, blinded study, which recruited adults undergoing routine colonoscopy in 6 general hospitals in the UK.
Participating colonoscopists were trained using the Narrow Band Imaging International Colorectal Endoscopic (NICE) classification.
By comparing the optical and histological findings in patients with only small polyps, the researchers determined test sensitivity at the patient level using 2 thresholds, including the presence of adenoma and need for surveillance.
The research team compared accuracy of identifying adenomatous polyps <10 mm at the polyp level using hierarchical models, allowing determinants of accuracy to be explored.
The team found that of the 1688 patients recruited, 43% had polyps <10 mm with 79% having only polyps <10 mm.
|Test sensitivity by narrow band imaging optical diagnosis was 83%|
Test sensitivity by narrow band imaging optical diagnosis was 83%, significantly less than the 95% sensitivity this study was powered to detect.
Test sensitivity was 73%.
Analyzed at the polyp level, the researchers noted that test sensitivity was 76%.
In fully adjusted analyses, the researchers observed that test sensitivity was 99% if two or more narrow band imaging adenoma characteristics were identified.
Neither colonoscopist expertise, confidence in diagnosis nor use of high definition colonoscopy independently improved test accuracy.
Professor Rees concludes, "This large multicenter study demonstrates that narrow band imaging optical diagnosis cannot currently be recommended for application in routine clinical practice."
"Further work is required to evaluate whether variation in test accuracy is related to polyp characteristics or colonoscopist training."