Adenoma Detection Rates Calculated Using All Exams Are Associated with Lower Risk for Post Colonoscopy Colorectal Cancer: Data From the New Hampshire Colonoscopy Registry.

Abstract

INTRODUCTION We used New Hampshire Colonoscopy Registry (NHCR) data to examine the association between post-colonoscopy colorectal cancer (PCCRC) risk and an adenoma detection rate (ADR) which was calculated using exams with all indications, as compared to ADR restricted to only screening exams. METHODS Our cohort study included NHCR patients with an index exam and at least one follow-up event, either a colonoscopy or a CRC diagnosis. Our outcome, PCCRC was any CRC diagnosed ≥ 6 months after an index exam. The exposure variable was endoscopist-specific ADR (ADR-A), calculated for all indications, divided into quintiles. We also compared the ADR-A to 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 to ADR-A's <23% (Reference) (23%-<29%: HR=0.56, 95%CI:0.36-0.87;29%-<34%: HR=0.60, 95% CI:0.38-0.94; 34%-<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;IQR:0.10) for endoscopists when using ADR-A versus ADR-S. DISCUSSION Our data demonstrating lower PCCRC risk in exams performed by endoscopists with higher ADR's calculated with all exams helps 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.