In this issue Long and colleagues1 present the third fully published report to describe that polyp detection during colonoscopy deteriorates during the endoscopy day or work shift.1–3 The causes of this deterioration are as yet unknown, but these studies have introduced yet another concern about detection during colonoscopy. Before we assume that deterioration in detection is inevitable during the working day, and institute steps such as shorter work shifts, fewer procedures per shift, etc, we need some additional information. For example, we should determine whether the deterioration effect is operator dependent. Only 1 of the 3 studies published so far has described whether variability exists between endoscopists in the deterioration effect, and there were some endoscopists who had detection rates that were the same in the morning and afternoon, or even better in the afternoon.3 If the effect occurs in some endoscopists and not others, it would argue against fatigue as the root cause, although perhaps some endoscopists are more subjected to fatigue than others. In addition, variability in the effect between endoscopists would suggest that the effect is correctable with either schedule changes or behavioral changes. Although not yet fully published, 2 studies presented at Digestive Disease Week 2010 did not find the deterioration effect during the working day,4,5 suggesting that the effect is not universal across endoscopy units, and another reported that detection rates were not affected by numbers of procedures performed.6 Whether these as yet unpublished studies mean that the effect is operator dependent, or that certain endoscopy unit processes or practice settings eliminate the effect, is uncertain at present. However, the available data suggest that the effect could be the result of a relatively small number of examiners who are either prone to fatigue or to rushing as the shift progresses. In this regard, it would help to know whether the deterioration effect is related only to the time of day, or perhaps is related more directly to the relationship between when the procedure starts compared with when it was scheduled. Lower polyp detection when behind in the schedule would suggest that rushing the inspection process contributes to the deterioration effect. Another topic of interest is how easily the effect can be corrected, that is does simply watching for the effect or by letting doctors know that it has occurred lead to a correction? In short, we have a description of the effect, and a strong suggestion that the effect is not universal across units or examiners, but do not know why it occurs. More research needs to be carried out to fully describe the deterioration effect during the working day, understand its basis, and discover how it can be fixed.
Many aspects of detection during colonoscopy remain poorly understood. For example, this new “deterioration during the working day” effect is superimposed on the phenomenon of variable detection between endoscopists.7–12 The problem of variable detection between endoscopists, although recognized for a longer period of time than deterioration during the working day, is also primarily understood at just a descriptive level. Thus, we have good evidence that variable detection between endoscopists occurs for cancers,13–15 for adenomas,7–12 and for serrated lesions,16,17 but we are far from full understanding of the underlying causes of variable detection. Worse detection on average by nongastroenterologists suggests that suboptimal training is a factor.13–15 Withdrawal time7,10,12 and withdrawal technique18,19 are associated with detection, but that is about as far as our understanding of procedural elements goes. What are the real reasons why some people go too fast or have poor technique or cannot see flat lesions?
One conclusion we can reach with confidence is that failed detection is a huge problem in colonoscopy. Colonoscopy is used around the world for evaluation of symptomatic patients and those with positive screening tests. Therefore, effective detection during colonoscopy is needed worldwide to maximize reduction in colorectal cancer incidence and mortality in high-risk patients. Colonoscopy is also used in several countries for screening average-risk persons. In this regard, variable and relatively poor proximal colon detection15,20,21 has contributed to recent questioning of the value of colonoscopy compared with sigmoidoscopy screening.22,23 Indeed, poor detection for adenomas and polyps has now been shown to produce colorectal cancer risk after colonoscopy on both sides of the colon.12,24 Given these factors, improving detection during colonoscopy and reducing the operator dependence of the procedure assumes a high level of importance.
Table 1 lists a variety of areas related to detection for which more research is needed. Undoubtedly, the list is far from complete. Further, no attempt was made to include study of detection technologies that are still in development in Table 1. On the positive side, the number of procedures available to study detection issues is stunning, as detection is the central goal of nearly all of the many millions of colonoscopies performed worldwide annually. Many private practice groups, and academic groups, perform sufficient volumes of colonoscopies that they could contribute substantially to answering detection questions.
In Table 1, I have roughly grouped major issues in detection into those that are descriptive of the problem, those that address fundamental causes of failures to detect and variable detection, and those that are directed to correction of failed and variable detection. The list does not include issues related to bowel preparation. Effective preparation can now be achieved with either split dosing or same day dosing, although certainly there are still large problems with tolerability of bowel preparations and persistent issues with safety.
With regard to underlying causes of failed and variable detection, there is little doubt that part of the problem is behavioral. In a recent study, video-recordings of colonoscopies by 7 endoscopists were made without their knowledge, and then the doctors were informed that video-recordings would be made for quality review, but without stating that earlier recordings had already been made.19 Blinded review of the recordings showed that all of the doctors performed better during colonoscopy withdrawal, some to a remarkable degree, when they knew they were being recorded. This means that endoscopists knew how to perform a careful colonoscopy, but did not demonstrate their best technique until they were told they were being watched. That finding suggests a behavioral issue, which may have a very complex explanation (Table 1). Some of the possible underlying causes of failed or variable detection might eventually lead to the conclusion that some individuals are just not suited for performing effective colonoscopy, a possibility supported by the observation that some doctors' adenoma detection rates could not be corrected by educational efforts or punitive threats.11 However, in other practices, improvement was achieved by simple maneuvers.25 More study is needed to develop a clear understanding.
Arguably, the study of corrective measures is most important, as poor detection can be corrected by education or a quality improvement measure or a new technology, then do we care about the underlying causes? Detection technologies have not been adequately evaluated for their capacity to improve poor detection. Thus, new detection technologies are often tested first for their overall effectiveness by high-level adenoma detectors. In this context, electronic highlighting methods have generally been ineffective in improving adenoma detection.26 However, in a study where initial white light detection was very poor, the use of narrow band imaging resulted in higher detection which then transferred to better white light detection as the study proceeded.27 Thus, a technology could have minimal effect in high-level detectors yet be useful in reducing variation in detection. In addition, evaluation of detection technologies and techniques in multiple studies is needed, as the utility of a given corrective method could be operator dependent. Thus, just as we are understanding that so many aspects of baseline white light colonoscopy technique vary between operators, therefore, a given corrective method might improve 1 style of withdrawal technique and not another.
We have now learned that deterioration of lesion detection during colonoscopy as the work day progresses, which occurs at least for some endoscopists, represents a new flaw in colonoscopy as a colorectal cancer prevention technique. This issue, and the issue of variable detection between endoscopists, as well as the issue of the limits of colonoscopy detection even in the most skilled operator's hands, represent important challenges to providing colonoscopy in an effective and efficient manner to the millions of patients who stand to benefit. The good news is that we are now recognizing these various problems with colonoscopy detection, and we have plenty of colonoscopy procedures available for study of the detection problems as well as potential methods for its correction. We also have plenty of potential colonoscopy investigators and many options to pursue as pathways of investigation (Table 1). Detection during colonoscopy should be considered an attractive area for investigator-initiated research by both community and academic colonoscopists. There will be remarkable gains in colorectal cancer prevention if we can successfully convert colonoscopy to a procedure that has very little operator dependence with regard to detection, instead of a whole lot of it.
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