Posted on September 21, 2022

Time to Increase Adenoma Detection Rate Benchmarks for Screening Colonoscopies  

Jeffrey Lee, MD, MPH

Research Scientist and Attending Gastroenterologist, Kaiser Permanente San Francisco Medical Center, San Francisco, CA


This summary reviews Schottinger JE, Jensen CD, Ghai NR, et al. Association of Physician Adenoma Detection Rates With Postcolonoscopy Colorectal Cancer. JAMA 2022; 7;327(21):2114-2122. DOI:10.1001/jama.2022.6644

Correspondence to Jeffrey Lee, MD, MPH. Associate Editor. Email:

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Question: What are the associations between physician adenoma detection rates (ADRs) and patients’ risk of post-colonoscopy colorectal cancer (PCCRC) across a broad range of ADR values?

Design: Retrospective cohort study.

Setting: Three community-based integrated healthcare settings in the United States: Kaiser Permanente Northern California, Kaiser Permanente Southern California, and Kaiser Permanente Washington.

Patients: Among 735,396 patients who had 852,624 negative colonoscopies (i.e., negative for CRC) performed by 383 physicians, 51.6% were females and the median age was 61.4 years (interquartile range [IQR]: 55.5-67.2).

Exposure: The ADR of each patient’s physician based on screening examinations in the calendar year prior to the patient’s negative colonoscopy.  ADR was evaluated as a continuous and dichotomous variable (i.e., less than or equal to or greater than the median). ADR was also evaluated as a categorical variable to assess potential threshold associations (i.e., <20%, 20%-24.9%, 25%-29.9%, 30%-34.9%, 35%-39.9%, 40%-44.9%, 45%-49.9%, and ≥50%).

Outcome: The primary outcome was PCCRC, diagnosed at least 6 months after any negative colonoscopy (all indications). Secondary outcomes were PCCRCs by location, stage, and stratified by sex, and PCCRC-related deaths.

Results: After 2.4 million person-years of follow-up, 619 PCCRCs and 36 related deaths were observed over a median follow-up of 3.25 years (IQR: 1.56-5.01). The median physician ADR was 28.3%. Higher physician ADRs were significantly associated with lower risks of PCCRC (hazard ratio [HR]: 0.97 per every 1% absolute ADR increase, 95% CI: 0.96-0.98) and related deaths (HR: 0.95 per every 1% absolute ADR increase, 95% CI: 0.92-0.99). Compared with physician ADR below the median (i.e., 28.3%), ADRs at or above the median were significantly associated with a lower risk of PCCRC (1.79 vs 3.10 cases per 10,000 person-years; HR: 0.61, 95% CI: 0.52-0.73). There was a similar reduction in PCCRC-related mortality (0.05 vs 0.22 cases per 10,000 person-years; HR: 0.26, 95% CI: 0.11-0.65). Although a clear threshold was not seen across the 8 ADR groups because of overlapping CIs, a physician ADR between 35%-39.9% was associated with the lowest risk of PCCRC compared with ADRs less than 20% (Figures 1 and 2).

Funding: National Cancer Institute/National Institutes of Health.


Figure 1. Cumulative Incidence of PCCRC Stratified by ADR

Figure 2: Risk of Post-Colonoscopy Colorectal Cancer (PCCRC) According to Adenoma Detection Rates (ADR)


Why Is This Important?
The beneficial effect of colonoscopy on reducing CRC incidence and mortality is largely derived from early detection and removal of adenomas.1 Studies have consistently shown the magnitude of this benefit varies based on the quality of the colonoscopy examination, particularly the ability to detect adenomas.2,3 To improve colonoscopy quality, multiple guidelines recommend physician ADR benchmarks of ≥20% for women, ≥30% for men, and ≥25% combined.4 However, these recommended ADR targets were based on studies that lacked sufficient precision and from time periods when physician ADRs were lower,2,3 leaving the question of whether ADR benchmarks should be increased or remain the same given improvements in imaging quality and increased emphasis on ADR measurements over the past decade.

This study remedies those limitations. It’s the largest cohort study (852,624 negative colonoscopies performed by 383 endoscopists) to demonstrate that higher physician ADR was significantly associated with lower risks of PCCRC, PCCRC-related death, and PCCRC by sex, stage, and location. Also, the study assessed colonoscopies performed between 2010-2017 vs the 1998-2010 timeframe used to identify minimum ADR thresholds of 25%. During the 2010-2017 timeframe, endoscopists routinely reported higher ADRs, partly based on improved bowel preparation techniques, improved endoscopic technology that provide better images, and increased awareness of the importance of ADRs. Thus, this study provides important data to re-assess minimum ADR thresholds as well as assessing whether or not there is an ADR threshold beyond which higher ADRs do not further lower PCCRC.

Key Study Findings
For each percentage point increase in ADR, the adjusted PCCRC risk and PCCRC-related death was 3% and 5% lower, respectively. Although an ADR threshold was not clearly seen in this study despite its large sample size, an ADR of 35%-39.9% demonstrated the largest reduction in PCCRC risk (HR: 0.41, 95% CI: 0.29-0.59) compared with an ADR <20%. This multi-center cohort study further validates the importance of physician ADR as the key quality indicator for colonoscopy and suggests that minimum and aspirational ADR targets should be increased during the next guideline update.

Sessile serrated lesions (SSLs) were included in the ADR calculation despite current recommendations in clinical practice to exclude them. Although SSLs are less prevalent compared to conventional adenomas, inclusion of these lesions make comparison across other studies challenging. Nevertheless, flat SSLs in the ascending colon are easily missed and known to be a common etiology for PCCRC.

My Practice
In our medical group, ADRs from screening colonoscopies are provided annually to all gastroenterologists along with other important colonoscopy quality indicators (e.g., cecal intubation rate) to facilitate self-assessment and performance improvement. In addition to measuring ADR, there are several tools and techniques I use to optimize adenoma detection. First, it is critical to use a high-definition colonoscope with image enhancement capabilities (e.g., narrow band imaging) to help detect and evaluate subtle lesions. Second, it is important to have a mindset for detecting flat polyps since these lesions are often missed. Third, I maximize mucosal exposure by “working the folds” (i.e., deflecting the tip of the colonoscope into the inner-haustral valley and exposing the proximal sides of each haustral folds), cleaning and suctioning any stool debris, and distending the lumen adequately. Fourth, I perform 2 or 3 passes in the right colon since adenomas are often missed in this location. Lastly, when available, I often use a distal attachment device such as a clear translucent cap to help expose the proximal sides of each haustral fold and improve mucosal exposure.

For Future Research
Larger studies with more power and longer follow-up are needed for identifying an ADR threshold. The current study lacks statistical power to determine if ADRs > 40% further lower PCCRC because relatively few endoscopists in this cohort had these very high ADRs. Future studies are also needed to evaluate the impact of ADR improvement over time on PCCRC and PCCRC-related deaths. Ultimately, future guidelines and position statements will update recommendations about including SSLs in ADR calculation, whether to limit ADR to only screening colonoscopies, and comment on whether an ADR > 25% is still an appropriate minimum threshold.

Conflict of Interest
Dr. Lee was a co-author and investigator of this study.


  1. Bibbins-Domingo K, Grossman DC, Curry SJ, et al; US Preventive Services Task Force. Screening for colorectal cancer: US Preventive Services Task Force Recommendation Statement. JAMA. 2016;315(23):2564-2575.
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