TTP1.10 Diurnal Variation in Adenoma Detection Rates During Colonoscopy: A Multicentre Retrospective Cohort Study

Aims The adenoma detection rate (ADR) is a crucial performance indicator in colonoscopy. This study primarily aimed to compare ADR between morning and afternoon colonoscopy sessions. The secondary aim was to evaluate the influence of patient-specific and colonoscopist-specific factors on ADR. Methods This was a multicentre retrospective observational study analysing colonoscopy data from three endoscopy units over six months. Exclusion criteria included incomplete colonoscopies, previous colorectal resections, patients aged 16 years or younger, and incomplete datasets. Data was analysed for patient demographics, colonoscopy reports, and pathology findings. ADR was defined as the percentage of colonoscopies in which at least one adenoma was detected and confirmed by histopathology. Results Out of 3,665 colonoscopies performed by 55 colonoscopists, 508 were excluded. The mean patient age was 59.5 years, with 52.3% being male. While the demographic distribution of sex and ethnicity was similar in both groups, the afternoon group had a higher percentage of patients aged 40-49 (16.0% vs 11.6%, p<0.001) and fewer aged 60-69 (25.9% vs 30.0%, p=0.012). Overall, ADR was significantly lower in afternoon sessions (14.4% vs 18.6%, p=0.002). Subgroup analysis indicated reduced ADR in males (18.6% vs 24.5%, p=0.020), those aged 60-69 (18.1% vs 25.3%, p=0.039), and procedures performed by nurse colonoscopists (10.5% vs 16.3%, p=0.007) in the afternoon sessions. Conclusion ADR is significantly lower in afternoon sessions, potentially due to increased workload from full-day schedules. Further research is necessary to determine whether this is due to the complexity of procedures or the effects of fatigue.