Time-of-day variation in the diagnostic quality of screening colonoscopies: a registry-based study

The diagnostic quality of screening colonoscopies has been found to differ between morning and afternoon. Specifically, the adenoma detection rate (ADR) is higher in the morning. Our aim was to assess if time-of-day dependent differences in colonoscopy quality exist in a Danish screening setting. Following national screening guidelines, an individual will be exempt from screening invitations for 8 years if the colonoscopy is without pathology. Therefore, it is of utmost importance to identify factors systematically affecting the detection of lesions.

This was a single-center study of screening colonoscopies performed between 2014 and 2018. Records were retrieved from the Danish Colorectal Cancer Screening Database and coupled with local data. The ADR and the cecal intubation rate were compared between morning (8-12 a.m.) and afternoon (12-4 p.m.) colonoscopies. Multivariate logistic regression analysis was performed.

A total of 3659 screening colonoscopies were included. The ADR was 51% in the morning and 58% in the afternoon. Multivariate analysis found this statistically significant, with the "afternoon vs. morning" odds ratio for adenoma detection being 1.4 (95% confidence interval 1.17-1.68; P<0.001). The cecal intubation rate was 95.6% in the morning and 94.7%, a non-significant difference.

The ADR of screening colonoscopies was higher in the afternoon. Our study highlights the need for local/regional evaluation of factors affecting colonoscopy quality to address such issues. A clean colonoscopy exempts the patient from subsequent screening invitations for 8 years. Therefore, any observed systematic differences in quality must be addressed and eliminated.