Adenoma Detection Rates Calculated Using All Examinations Are Associated With Lower Risk for Postcolonoscopy Colorectal Cancer: Data From the New Hampshire Colonoscopy Registry

INTRODUCTION: We used New Hampshire Colonoscopy Registry data to examine the association between postcolonoscopy colorectal cancer (PCCRC) risk and an adenoma detection rate (ADR) which was calculated using examinations with all indications, as compared with ADR restricted to only screening examinations. METHODS: Our cohort study included New Hampshire Colonoscopy Registry patients with an index examination and at least 1 follow-up event, either a colonoscopy or a CRC diagnosis. Our outcome, PCCRC, was any CRC diagnosed ≥6 months after an index examination. The exposure variable was endoscopist-specific all-examination ADR (ADR-A), calculated for all indications, divided into quintiles. We also compared the ADR-A with a screening ADR (ADR-S). Cox regression was used to model the hazard of PCCRC on ADR, controlling for age, sex, and other covariates. RESULTS: In 32,535 patients, a lower hazard for PCCRC (n = 178) was observed for ADR-A's ≥ 23%, as compared with ADR-A's <23% (reference) (23% to <29%: hazard ratio (HR) = 0.56, 95% CI: 0.36–0.87; 29% to <34%: HR = 0.60, 95% CI: 0.38–0.94; 34% to <44%: HR = 0.43, 95% CI: 0.29–0.65; and ≥44%: HR = 0.32, 95% CI: 0.16–0.63). The highest quartile of ADR-A (42%+) (HR = 0.41, 95% CI: 0.23–0.75) had a similar protection from PCCRC as the highest quartile of ADR-S (35%+) (HR = 0.38, 95% CI: 0.21–0.70). We observed 95% CIs for ADR's were 28% narrower (median = 0.72; interquartile range (IQR): 0.10) for endoscopists when using ADR-A vs ADR-S. DISCUSSION: Our data demonstrating lower PCCRC risk in examinations performed by endoscopists with higher ADR's calculated with all examinations help to validate ADR-A as a quality measure. ADR-A may also increase precision of the calculated ADR. Endoscopists should strive for a higher ADR-A with 44% as an aspirational target.