The Time to Increase Our Adenoma Detection Rates Is Now

David A. Johnson, MD


August 30, 2021

This transcript has been edited for clarity.

Hello. I'm Dr David Johnson, professor of medicine and chief of gastroenterology at Eastern Virginia Medical School in Norfolk, Virginia.

Using adenoma detection rate (ADR) as a key measure of colonoscopy quality has been with us for nearly two decades. The recent publication of two studies about ADR presents a good opportunity to assess where we've been, where we're going, and if and how we should move our target goalposts.

Setting the Minimum ADR Threshold

In 2002, the US Multi-Society Task Force on Colorectal Cancer first recommended using ADR as a benchmark for determining colonoscopy quality based on prevalence studies of adenomas detected on screening examinations. At that time, the Task Force stated that the minimum ADR should be 20% on the initial screening exam, based on a blended rate of 25% for men and 15% for women.

In later years, this was adjusted up to a 25% blended rate — 30% for men and 20% for women — on the initial screening examination.

Subsequent guidelines and expert consensus recommendations from the Task Force, the American College of Gastroenterology (ACG), and others have continued to recommend a 25% minimum threshold for any screening examinations for average-risk patients.

Several studies have demonstrated beyond question that ADR offers substantial protective benefits by decreasing the rate of interval cancer and associated death. There was incredibly persuasive data from Poland showing this in 2017. Similarly, Dr Douglas Corley and colleagues reported last decade that by increasing ADR by 1%, you essentially decrease the risk for interval colon cancer by 3% and the risk for colon cancer–related deaths by 5%.

Collectively, these findings have led to categoric agreement that ADR should be measured as a part of screening quality recommendations. In fact, not only should it be measured, but the US Multi-Society Task Force guidelines recommend that patients should actually be asking their physicians what their ADR is.

Reconsidering Where Our ADR Goalposts Be Set

An excellent analysis has just been published looking at the GI Quality Improvement Consortium, Ltd. (GIQuIC) registry, which now includes data from over 15 million colonoscopies and endoscopies conducted by 4500 practicing physicians — representing about 40% of the gastroenterologists in the United States — at over 700 centers. This analysis of the GIQuIC registry provides a perfect opportunity to reconsider if, and by how far, we should be moving our goalposts when it comes to setting minimum ADR thresholds.

Dr Aasma Shaukat and colleagues looked at GIQuIC registry data for a 4-year window (2014-2018) in adults aged 50-89 years. Lo and behold, they found a demonstrable increase of approximately 4% in ADR from screening colonoscopies during that time. The average ADR per endoscopist was 36.8%, far beyond the 25% blended rate reported previously. The average ADR was 44% in men and 31% in women.

They found that adequate colon preparation also increased by a little more than 2.5% over that time, representing a significant improvement (P < .0001). This likely reflects the better outcomes that come from using split-dose preparation as a standard of care, in line with what the guidelines say, and is yet a measure by which physicians should be judged for the quality of colonoscopies they perform.

There's been a growing recognition among experts that, ideally, the target for ADR should be closer to the 45%-50% range. We're certainly seeing those ranges in the centers of excellence that have looked closely at this.

ADR, Beyond Initial Screening

New findings are also shedding light on increasing ADR beyond just screening examinations.

A recently published study looked at data from over 2600 colonoscopy exams performed by 21 endoscopists at two different Veterans Affairs centers. Investigators found that the inclusion of surveillance, screening, and diagnostic exams all equated to a blended ADR of about 50%.

We know that surveillance exams typically derive a 7%-10% increase in the ADR. However, inclusion of ADR for nonscreening purposes makes it easier to tabulate the overall figures from these exams. Certainly, centers that have lower screening rates may be able to tabulate them more easily using this approach. That's also the direction in which the experts are starting to move, although it's not the official recommendation at present.

Another thing to remember is that in fecal immunochemical test (FIT)–positive indications, the minimum targets for ADR are defined in the most recent guidelines at 45% for men and 35% for women, for a 40% blended ADR. Some data suggest that ADR for FIT-positive patients should be in the range of 60%-70%. Therefore, if you're in a system using FIT testing as an initial screening exam, you should really be recording the ADR, at least in those who are FIT positive.

Tips for Increasing Your ADR

The question then becomes, how can you obtain this higher level of ADR if you're not currently? I have some tips for that.

Taking a second look at the right colon is something that I routinely do and is very easy, with retroflexed and forward views having been shown to be equivalent in this regard. Attaching a mucosal exposure device to the tip of a colonoscope, using split-dose bowel preparations, and implementing longer withdrawal times have variously been shown to increase the ADR. The use of advanced imaging with chromoendoscopy, narrow-band imaging, and high-definition scopes has also been shown to have this effect. Finally, there is a growing recognition that ADR increases with the use of artificial intelligence, and the implementation of specific computer-assisted device programs may hopefully allow us to achieve a higher ADR.

There is one caveat to consider in that these results come from patients aged 50 years and older. Although this was the target screening age based on previous recommendations, it has since shifted to age 45 years and older. I've spoken to the authors of the GIQuIC registry analysis, who have informed me that they've already looked at this updated age group. There is a manuscript in process, with plans to present some of these data at the ACG meeting in October, so we'll have to stay tuned to hear more about that.

No Time Like the Present

When it comes to increasing our ADR, we need to get there sooner rather than later, given that colon cancer is still a very prevalent and preventable problem. That will require us to start moving the goalposts now. There is no question that we are well past the 25% thresholds reported earlier, and likely way below achieving the thresholds reported in these recent studies, even when considering that they may be recalculated for patients aged 45 years and older going forward.

It's all about quality. We need to start revising our internal quality assessments and not assuming that an ADR of 25% is adequate for quality performance. We can nudge the ADR goalpost now — just how far we nudge it is still to be determined. However, I think it's unquestionable that we can start moving in that direction, even as we await further data.

I'm Dr David Johnson. Thanks again for listening.

David A. Johnson, MD, a regular contributor to Medscape, is professor of medicine and chief of gastroenterology at Eastern Virginia Medical School in Norfolk, Virginia, and a past president of the American College of Gastroenterology. His primary focus is the clinical practice of gastroenterology. He has published extensively in the internal medicine/gastroenterology literature, with principal research interests in esophageal and colon disease, and more recently in sleep and microbiome effects on gastrointestinal health and disease.

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