Improving measurement of the adenoma detection rate and adenoma per colonoscopy quality metric: the Indiana University experience

Background: The adenoma detection rate (ADR) is a validated marker of colonoscopy quality. However, the optimal measurement method is unclear. Objective: The aims of our study were to (1) define benchmarks for the number of adenomas per screening colonoscopy (APC) quality metric; (2) study the association between ADRs for screening, surveillance, and diagnostic indications; and (3) explore the association of the screening ADR with an overall ADR inclusive of all colonoscopy indications. Design: Retrospective study. Setting: University hospital and associated ambulatory surgery center endoscopy units. Patients: Patients aged >= 50 years who underwent colonoscopy for screening, surveillance, or diagnostic indications by 20 endoscopists between January 1, 1999 and April 30, 2012. Intervention: Colonoscopy. Main Outcome Measurements: ADR, APC for screening, surveillance, and diagnostic indications. Results: A total of 21,766 colonoscopies were included. The indication was screening in 7434 (34.2%), surveillance in 8338 (38.3%), and diagnostic in 5994 (27.5%). The screening ADRs and APCs were significantly correlated (R = 0.91; P < .0001). For men, an ADR of 25% corresponded to an APC of 0.46 (95% confidence interval [CI], 0.35-0.57); for women, an ADR of 15% corresponded to an APC of 0.20 (95% CI, 0.13-0.27). Overall, the ADR stratified by colonoscopy indication was highest for surveillance, followed by screening, then diagnostic. For men, a screening ADR of 25% corresponded to a surveillance ADR of 31.9% (95% CI, 24.8%-38.9%); for women, an ADR of 15% corresponded to a surveillance ADR of 24.3% (95% CI, 18.3%-30.5%). The corresponding diagnostic ADRs were 17.0% (95% CI, 12.4%-21.6%) and 15.4% (95% CI, 11.5%-19.3%), respectively. There was significant correlation between screening ADR and an overall ADR inclusive of all colonoscopy indications. Limitations: External generalizability, retrospective design. Conclusion: We propose minimum screening APC detection benchmarks of 0.50 for men and 0.20 for women. ADRs for screening, surveillance, and diagnostic colonoscopy are correlated and can be used to derive a simplified overall ADR inclusive of all colonoscopy indications.