SAN DIEGO — A year-long study surprised investigators when results showed that increased detection of some adenomas using high-definition white light colonoscopy did not produce a “learning effect” leading to increased detection using standard-definition white light colonoscopy.
At least one previous study has suggested that getting accustomed to using high-definition colonoscopy with or without narrow-band imaging to identify previously unseen adenomas produced a cross-over learning effect that helped endoscopists recognize similar lesions using standard-definition colonoscopy, thus increasing adenoma detection with both technologies (Gut 2008;57:59-64).
In the current comparison, however, the adenoma detection rate for standard-definition white light colonoscopy did not increase significantly over the course of the study and remained significantly lower than detection with high-definition equipment, Dr. Anna M. Buchner reported at the annual meeting of the American College of Gastroenterology.
“There wasn't as much learning effect as we thought,” Dr. Kenneth R. DeVault, a coinvestigator in the study, said at a press briefing.
They conducted a “natural experiment” from October 2006 to March 2007 at their institution, the Mayo Clinic in Jacksonville, Fla., when the clinic wanted to upgrade to high-definition equipment but lacked the funds to replace all their colonoscopes at once, Dr. DeVault said.
They put new high-definition white light colonoscopes in three rooms for routine colonoscopies and randomized patients and physicians to one of these rooms or one of three rooms with standard-definition equipment.
High-definition white light colonoscopy used for 1,204 patients showed significantly better detection rates for all polyps (42%), hyperplastic polyps (20%), and adenomas (29%), compared with detection rates using standard-definition white light colonoscopy in 1,226 patients (38% for all polyps, 17% for hyperplastic polyps, and 24% for adenomas), reported Dr. Buchner, who is now with the University of Pennsylvania, Radnor.
Small or moderate-sized adenomas were more likely to be detected by high-definition colonoscopy than with standard-definition imaging: Detection rates for adenomas sized 0-5 mm were approximately 21% with high-definition colonoscopy and 17% with standard-definition equipment. Detection rates for adenomas sized 6-9 mm were approximately 8% with high-definition colonoscopy and 6% with standard-definition technology. High-definition colonoscopy also was more likely to detect polyps on the left side of the colon, she added.
For adenomas larger than 10 mm, however, detection rates were similar with the two techniques. Over the course of the study, detection of polyps overall increased, but adenoma detection did not.
The general characteristics of the patients and of the procedures done using standard-definition colonoscopy did not change significantly between the 6 months prior to introduction of high-definition colonoscopy in some procedure rooms and the ensuing study period, Dr. Buchner noted.
The investigators reported having no conflicts related to this study.
Detection of adenomas remained significantly lower with the standard-definition equipment.
Source DR. BUCHNER