Effect of Glucagon-Like Peptide-1 Receptor Agonists on Bowel Preparation for Colonoscopy

INTRODUCTION: Inadequate bowel preparation can result in decreased diagnostic accuracy and therapeutic safety of colonoscopy for colon cancer screening. The Boston Bowel Preparation Scale (BBPS) has been used to assess the quality of bowel preparation. Glucagon-like peptide-1 receptor agonists (GLP-1RA) are commonly used medications for diabetes mellitus and obesity that are known to delay gastrointestinal motility. We hypothesized that the use of GLP-1RA would be associated with decreased quality of bowel preparation. METHODS: We performed a retrospective cohort study of patients who underwent screening or surveillance colonoscopy at a large academic medical center between December 2021 and December 2022. We included patients taking any GLP-1RA for diabetes or obesity during colonoscopy defined as our cases, and patients who were prescribed GLP-1RA at one point but not within 3 months of colonoscopy defined as our controls. We excluded patients on any promotility or antimotility agents and those without BBPS recorded on their procedure report. Independent t test assessed statistical differences in the case and control groups to compare the quality of bowel preparation for continuous variables, and the χ 2 test was used for categorical variables. Multivariate linear regression including diabetes as a covariate was also performed for continuous variables, and multivariate logistic regression was performed for categorical variables. RESULTS: A total of 446 patients were included in the study, comprising 265 (59%) cases and 181 controls (41%). There were no statistically significant differences between groups at baseline except for the diagnosis of diabetes ( P = 0.001) with a higher proportion of patients with diabetes in the cases. The mean BBPS was significantly higher in controls (7.0 ± 1.9 vs 7.5 ± 2.4, P = 0.046) when controlling for diabetes. The percentage of patients with a total BBPS score of <5 was significantly higher in cases (15.5% vs 6.6%, P = 0.01). The proportion of patients who required a repeat colonoscopy due to poor bowel preparation was also significantly higher in cases (18.9% vs 11.1%, P = 0.041). DISCUSSION: The use of GLP-1RA was associated with a statistically significantly lower quality of bowel preparation, with additional clinical significance given a notable difference in the need for a repeat colonoscopy. It will be essential to understand the cumulative effect of medications that may delay gastric emptying on the quality of bowel preparation to better understand the appropriate measures and counseling that need to be taken before undergoing outpatient colonoscopies.