Adenoma detection rates vary minimally with time of day and case rank: a prospective study of 2139 first screening colonoscopies

Background: Adenoma detection rate is an important measure of colonoscopy quality; however, factors including procedure order that contribute to adenoma detection are incompletely understood. Objective: The aim of this study was to prospectively evaluate factors associated with adenoma detection rate. Design: Prospective cohort study. Data were collected on patient and physician characteristics, trainee participation, time of day, and case rank. Setting: Outpatient tertiary-care center. Patients: This study involved consecutive patients presenting for first screening colonoscopies. Main Outcome Measurements: Adenoma and polyp detection rates (proportion of cases with one or more lesion detected) and ratios (mean number of lesions detected per case). Results: A total of 2139 colonoscopies were performed by 32 gastroenterologists. Detection rates were 42.7% for all polyps, 25.4% for adenomas, and 5.0% for advanced adenomas. Adenoma detection was associated with male sex and increasing age on multivariate analysis. In the overall study cohort, time of day and case rank were not significantly associated with detection rates. In post hoc analysis, polyp and adenoma detection rates appeared lower after the fifth case of the day for endoscopists with low volumes of cases and after the tenth case of the day for endoscopists with high volumes of cases. Limitation: Single center. Conclusion: Overall, time of day and case rank did not influence adenoma detection rate. We observed a small but significant decrease in detection rates in later procedures, which was dependent on physician typical procedure volume. These findings imply that colonoscopy quality in general is stable throughout the day; however, there may be a novel "stamina effect" for some endoscopists, and interventions aimed at improving colonoscopy quality need to take individual physician practice styles into consideration. (Gastrointest Endosc 2012;75:554-60.)