Improving Measurement of Adenoma Detection: The Indiana University Experience

Abstract

Purpose: The adenoma detection rate (ADR) is a validated measure of colonoscopy quality. However, the restriction to screening colonoscopy may be a barrier to uptake. Knowledge of the ADR in nonscreening groups, and its relation to the screening ADR, might allow expansion of the ADR to include surveillance and diagnostic indications and simplify calculations. The aims of this study were: (1) to study the correlation between ADRs for screening, surveillance, and diagnostic indications, and (2) explore the association of the screening ADR with an overall ADR inclusive of all colonoscopy indications. Methods: We performed a retrospective review of a prospectively updated database at a University hospital and associated ambulatory surgery center endoscopy units. Colonoscopies performed by 20 attending gastroenterologists on patients aged ≥ 50 between 1/1/1999 and 4/30/2012 were reviewed. ADR was defined as the proportion of colonoscopies in which at least one adenoma was detected. Pearson correlation coefficients were calculated to evaluate the association of the ADRs of the three colonoscopy indication categories (screening, surveillance, or diagnostic). The second study aim was addressed using a bootstrap analysis. We calculated the Pearson correlation coefficient of screening ADR with overall ADR, and estimated the overall ADR corresponding to screening ADRs of 15%, 20%, 25%, 30%, 40%, and 50% for patient populations with varying proportions of screening, surveillance, and diagnostic colonoscopies. Results: 21,766 colonoscopies were included; indication screening in 7,434 (34.2%), surveillance in 8,338 (38.3%), and diagnostic in 5,994 (27.5%). Endoscopist ADRs are shown in Table 1. A consistent pattern was observed, with ADR highest for surveillance, followed by screening, then diagnostic indications. ADRs for screening and surveillance, and screening and diagnostic indications, were significantly correlated (R=0.77, p<0.0001; R=0.56, p=0.01, respectively). The correlation between ADRs for surveillance and diagnostic was borderline significant (R=0.42, p=0.07). For males, screening ADR of 25% corresponded to surveillance ADR of 31.9% (95% CI: 24.8%-38.9%); for females, ADR of 15% corresponded to a surveillance ADR of 24.3% (18.3%-30.5%). The corresponding diagnostic ADRs were 17.0% (12.4%-21.6%) and 15.4% (11.5%-19.3%), respectively. The results of the bootstrap analysis exploring the association of screening ADR with the overall ADR are shown in Table 2.Table 1: ADRs for screening, surveillance, and diagnostic colonoscopiesTable 2: Screening ADR-Overall ADR associationsConclusion: ADRs for screening, surveillance, and diagnostic colonoscopy are correlated and can be used to derive a simplified overall ADR inclusive of all colonoscopy indications. Our findings provide a framework for endoscopists to calculate their ADRs in different practice settings.