Post written by Joseph D. Feuerstein, MD, from the Center for Inflammatory Bowel Disease, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA.
The focus of this study was to assess the benefits of adding chromoendoscopy to enhance our ability to screen for colorectal cancer in patients with longstanding inflammatory bowel disease affecting over 1/3 of their colon. While this technique has been advocated by many as being more effective at detecting dysplasia, the actual benefit does not seem to have been replicated in all studies. In general, high-definition colonoscopy provides an excellent image of the bowel mucosa, and the ability to detect even small, subtle changes has changed dramatically compared to when standard-definition scopes were available. Additionally, studying chromoendoscopy can be challenging; when studies are not designed as randomized control trials, there is always a risk of inadvertent bias in retrospective and observational studies that may lead to different results. As a result, we decided to evaluate the data as a meta-analysis, assessing the overall quality of evidence when comparing studies using standard-definition colonoscopy with biopsies to chromoendoscopy and high-definition colonoscopy with biopsies to chromoendoscopy. This comparison was done separately for randomized control trials and for non-randomized control trials to assess if there was a difference.
The study is important as not every new and additional technique or technology is going to enhance our ability to detect dysplasia. While it is clear that chromoendoscopy can pick up very small lesions, it is important to assess the quality of this technique in properly designed trials that provide higher-quality evidence to determine its overall efficacy. Not everyone is trained or skilled in chromoendoscopy, and if the technique does not enhance our screening or surveillance in patients with inflammatory bowel disease then one should focus more on just a high-definition white-light colonoscopy and spend more time evaluating the colon this way.
Our study found that in randomized control trials, chromoendoscopy was superior to standard-definition colonoscopy, but there was no difference when compared to high-definition colonoscopy (RR 1.36; 95% CI 0.84-2.18. This evidence was rated as moderate quality using GRADE methodology. In contrast, the non-randomized control trials showed chromoendoscopy was more beneficial than both standard- and high-definition colonoscopy with very low-quality evidence.
This discrepancy in findings between the RCT and non-RCT data was thought to be due to the differences in the study designs and overall quality of the studies. Given that the RCT data is a higher-quality study design and with moderate-quality evidence, it appears that our current white-light high-definition colonoscopes are as effective as chromoendoscopy.
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