Application of a conversion factor to estimate the adenoma detection rate from the polyp detection rate

Background: The adenoma detection rate (ADR) is a quality benchmark for colonoscopy. Many practices find it difficult to determine the ADR because it requires a combination of endoscopic and histologic findings. It may be possible to apply a conversion factor to estimate the ADR from the polyp detection rate (PDR). Objective: To create a conversion factor that can be used to accurately estimate the ADR from the PDR. Design: This was a retrospective study of colonoscopies performed by board-certified gastroenterologists to determine the average adenoma to polyp detection rate quotient (APDRQ) for all endoscopists, individually and as a group. Setting: Academic group practice. Intervention: The group average APDRQ was used as a conversion factor for the endoscopist's PDR to estimate the ADR. Main Outcome Measurements: The strength of the relationship between the estimated ADR and the actual ADR determined by Pearson's correlation coefficient. Results: A total of 3367 colonoscopies performed by 20 staff gastroenterologists were included. The average ADR for all indications, all patient age groups, and both sexes was 0.17 (range 0.09-0.27, standard deviation 0.05). The average APDRQ was 0.64 (range 0.46-1.00, standard deviation 0.13). The correlation between the estimated ADR and the actual ADR was 0.85 (95% CI, 0.65-0.93, P = .000001). Limitations: Retrospective study in 1 practice setting with all patient types. Conclusions: The use of a conversion factor can accurately estimate the ADR from the PDR. Further study is needed to determine whether such a conversion factor can be applied to different practice settings and patient groups. (Gastrointest Endosc 2011;73:493-7.)