Proposal of high-risk adenoma detection rate as an impactful, complementary quality indicator of colonoscopy

Background and aims: Adenoma detection rate (ADR), a validated quality indicator (QI) of colonoscopy, does not take into account risk stratification of adenomas. Low-risk adenomas are not associated with a significantly increased risk of future colorectal cancer (CRC). On the other hand, high-risk adenomas (HRA) are associated with up to six fold higher risk of future CRC. Therefore, HRA detection rate (HR-ADR) as a QI in addition to ADR may further enhance the efficacy of screening colonoscopy. Our aim was to calculate ADR and HR-ADR in a large cohort of average risk screening colonoscopy patients and propose HR-ADR which correlates with current threshold ADR. Methods: This is a retrospective chart review of all colonoscopies performed in patients aged ≥ 50 years at our institution between 2012 and 2014. Average risk patients who had complete colonoscopy with good, excellent and adequate bowel preparation were included. Overall and gender-specific ADR and HR-ADR were calculated. HR-ADR was defined as proportion of colonoscopies with HRA. Results: Among 4158 colonoscopies included, ADR was 26.4 ± 10.9% overall, 32.7 ± 14.5% in men, and 22.1 ± 12.6% in women. HR-ADR was 8.0 ± 5.7% overall, 10.2 ± 8.6% in men, and 6.1 ± 6% in women. There was only moderate correlation between ADR and HR-ADR [r = 0.57 (0.40–0.70)]. HR-ADR corresponding with minimum threshold ADR of 30% in men and 20% in women were calculated to be 7% in men and 4% in women. Conclusions: HR-ADR correlates only moderately with ADR. Based on the current threshold ADRs, we propose a benchmark HR-ADR of 7% in men and 4% in women as complementary QI to ADR.