Higher Polyp Detection Rate and Cecum Intubation Rate in Morning Shift Compared to Afternoon Shift: A Multicenter Large Cohort Retrospective Study

Background: Colorectal cancer (CRC) is the third most commonly occurring cancer worldwide. There are conflicting reports on whether colonoscopies performed during the morning shift have higher adenoma detection rates. Objectives: To investigate the differences in polyp detection rate (PDR) in colonoscopies between morning and afternoon shifts. Methods: In a retrospective, multicenter study involving a large cohort, we analyzed all colonoscopies conducted between 2016 and 2023 across seven endoscopy departments. The PDR was compared between morning and afternoon shifts. Results: We included 368,997 colonoscopies: 213,795 (57.9%) performed during the morning shift and 155,202 (42.1%) during the afternoon shift. Patients undergoing colonoscopies during the morning shift were more frequently female (53.8% vs. 51%, P < 0.001) and tended to be older compared to those in the afternoon shift (average age of 56.97 ± 12.6 vs. 55.6 ± 12.9, P < 0.001). Colonoscopies conducted during the morning shift exhibited a higher cecum intubation rate (CIR) (96.7% vs. 95.6%, P < 0.001). During the morning shift, higher rates of PDR (32.9% vs. 29.9%, P < 0.001) were observed. In the multivariate analysis, after adjusting for other variables, age, male sex, polyp follow-up, fecal occult blood test, morning shift, familial history of CRC, and rectal bleeding demonstrated statistically significant associations (P < 0.001) for PDR. Conclusions: Colonoscopies during the morning shift yielded a higher PDR and CIR than those in the afternoon. To improve this rate, endoscopists working the afternoon shift must be provided with the right conditions.