Time of day variation in polyp detection rate for colonoscopies performed on a 3-hour shift schedule

Background Recent research suggests that the colonoscopy polyp detection rate (PDR) varies by time of day, possibly because of endoscopist fatigue. Mayo Clinic Rochester (MCR) schedules colonoscopies on 3-hour shifts, which should minimize fatigue. Objective To examine PDR variation with the MCR shift schedule. Design Retrospective cohort. Setting Outpatient tertiary-care center. Patients This study involved completed outpatient colonoscopies in 2008. Procedures were excluded for lack of withdrawal time stamps, indications other than average-risk screening, inadequate bowel preparation, fellow participation, or performance by endoscopists with a low number of endoscopies performed. Intervention None. Main Outcome Measurements PDR (colonoscopies with ≥1 polyp divided by total number of colonoscopies) by shift of day. Results We analyzed 3846 colonoscopies. PDR varied significantly by shift ( P = .008) on univariate analysis; results for shifts 1 and 3 were similar (39.0% vs 38.7%, respectively) whereas shift 2 had the highest PDR (44.7%). Mean withdrawal times were stable ( P = .92). PDR also varied significantly ( P < .0001) by month of year on univariate analysis. On multivariate analysis, patient age ( P < .0001), patient gender ( P < .0001), endoscopist mean withdrawal time ( P < .0001), month of year ( P = .0002), endoscopist experience ( P = .04), and shift of day ( P = .048) significantly predicted PDR. Limitations Retrospective study. Conclusion MCR's 3-hour shift schedule does not show a decrease in PDR as the day progresses, as seen in other recent studies. Intervention trials at other institutions could determine whether alterations in shift length lead to PDR improvements.