Adenoma Detection Rate Does Not Differ in Screening Colonoscopies Performed in the Morning or Afternoon: 1555

Introduction: Adenoma detection rate (ADR) is an accepted indicator of colonoscopy quality. Previous publications have suggested that colonoscopies performed in the afternoon had lower ADR than those performed in the morning. It is postulated that a decrease in ADR is noted in the afternoons in part because of physician fatigue. This study aims to reexamine this relationship for patients undergoing screening colonoscopies. Methods: A retrospective review was conducted of electronic records of all screening colonoscopies performed at an urban university medical center hospital and affiliated ambulatory surgery center (ASC) in a 12-month period. Average risk screening colonoscopies were included. Procedures for other indications were excluded from the analysis. Patient age, gender and race were. Colonoscopies were first categorized based upon the location (hospital or ASC) and divided into AM and PM group to evaluate for variation in ADR with respect to time of the day. A faculty gastroenterologist performed each procedure with or without trainee involvement. Microsoft Excel was used to generate a database that maintained patient confidentiality. Statistical analysis was performed using Fisher Exact test, with significance set at p < 0.05. The study was approved by the university institutional review board. Results: 1528 colonoscopy records (871 women, 657 men) were reviewed. Eight faculty gastroenterologists performed all colonoscopies. 961 screening colonoscopies were scheduled at the hospital and 567 cases were completed at the ASC. There were 460 Caucasian patients, 771 African-American patients, 117 Hispanic patients, and 180 patients of other or undocumented ethnicity. The mean patient age was 57.9 years (+/- 8.22). Adenomas were detected in 431 patients (ADR 44.8%) whose procedures were performed at the hospital. There were 206 patients with adenomas (ADR 36.3%) at the ASC. The average withdrawal times were the same at the ASC (13.5 minutes +/- 6.58) and hospital (13.55 minutes +/- 6.56). The ASC's ADR for AM (n=335) and PM (n=232) cases were 37.7% and 34.4% (p=0.47) respectively. The hospital's ADR for AM (n=520) and PM (n=441) procedures were 45.7% and 43.7% (p = 0.60) respectively. Conclusion: This study revealed that there is no significant difference in ADR in screening colonoscopies performed in the morning or in the afternoon. As this is contrary to previously published data, further evaluation with large, prospective studies are necessary to reconcile the findings.