Provide total screening colonoscopies and adenoma counts to visualize performance metrics.
Guidelines & Evidence
Clinical Details
Section 1
When to Use
When to Use
Primary quality metric for screening colonoscopy in average-risk adults (age ≥45 or 50)
To benchmark individual endoscopist performance against national standards
To determine appropriate surveillance intervals for patients with negative screening exams
Monitoring efficacy of technique (withdrawal time, mucosal inspection, bowel prep utility)
Patient Population
Calculation is restricted to asymptomatic, average-risk adults undergoing their first screening colonoscopy. Excludes surveillance (history of polyps), diagnostic (haematochezia, weight loss), and therapeutic (EVAL for positive FIT/Cologuard) procedures.
When Not to Rely on ADR Alone
Diagnostic or therapeutic colonoscopies — ADR is not validated as a quality metric in symptomatic patients
Procedures with inadequate bowel preparation (BBPS < 6) — mucosal visibility is compromised
Incomplete procedures (failed caecal intubation) — right-sided adenomas may be missed
High-risk surveillance — patients with inflammatory bowel disease or polyposis syndromes require different metrics
Section 2
Formula & Logic
Calculation Formula
ADR (%) = (Number of screening colonoscopies with ≥1 adenoma) / (Total screening colonoscopies performed) × 100
Benchmark Thresholds (ASGE/ACG 2015)
Overall ADR
≥ 25%
Male Patients
≥ 30%
Female Patients
≥ 20%
Key Components
01
Histological Confirmation: Only lesions confirmed by pathology as tubular, tubulovillous, or villous adenomas (including those with HGD) count.
02
The "One-and-Done" Bias: ADR only cares if *one* adenoma is found. High-quality endoscopists should also monitor Mean Adenomas per Colonoscopy (MAP) to ensure thorough inspection after the first finding.
03
Sessile Serrated Lesions (SSLs): Traditional ADR ignores SSLs, but "Serrated Detection Rate" (SDR) is an increasingly tracked secondary metric (benchmark ≥ 7-10%).
Section 3
Pearls/Pitfalls
The Corley Correlation
The ADR is the only colonoscopy quality metric directly linked to the prevention of "Interval" Colorectal Cancer (cancer diagnosed between screening and next scheduled surveillance).
Impact of Improvement
For every 1% increase in an endoscopist's ADR, there is a corresponding 3% decrease in the risk of interval cancer and a 5% decrease in the risk of fatal colorectal cancer.
Withdrawal Time (WT)
Withdrawal time must average ≥ 6 minutes in normal (negative) screening exams
High-definition (HD) colonoscopes significantly improve ADR vs standard definition
Split-dose bowel preparation is mandatory to maximise right-sided mucosal visibility
Techniques like caecal retroflexion and distal attachment devices (caps) increase detection in difficult folds
Section 4
Next Steps
Surveillance Intervals (USMSTF)
01
High ADR Endoscopist + Clean Colon: Re-screening in 10 years (average risk).
02
Non-satisfactory ADR: Consider shorter intervals or repeat if prep was suboptimal.
03
High Adenoma Burden: Finding ≥ 3 small adenomas or 1 large (>10mm) adenoma mandates 3-5 year surveillance regardless of ADR.
Complementary Metrics
Boston Bowel Prep Scale (BBPS)
Caecal Intubation Rate (CIR) — Target ≥ 95%
Serrated Detection Rate (SDR) — Target ≥ 7%
Withdrawal Time (WT) — Target ≥ 6 mins
Section 5
Evidence Appraisal
Primary Quality Standard
Quality indicators for colonoscopy.
Rex DK et al. • Gastrointestinal Endoscopy. 2015;81(1):31-53. ACG-ASGE Task Force update establishing the 25% ADR benchmark.
The concept of ADR was introduced in the early 2000s as a way to objectify endoscopist skill beyond simple "re-screening at 10 years." It shifted endoscopy from a "procedural" focus to a "pathological" focus. It is currently the most scrutinized metric in US gastroenterology.
