Obesity and Body Mass Index are Not Associated with Suboptimal Quality of Bowel Preparation for Colonoscopy

Background Obesity and body mass index (BMI) have been reported as risk factors associated with inadequate bowel preparation, however, conflicting results have been consistently reported. This study aims to explore the association between obesity and the quality of bowel preparation. Methods We evaluated the efficacy of bowel preparation and colonoscopy outcomes according to obesity and BMI in subjects who underwent screening colonoscopy at a single hospital between January 1, 2021, and December 31, 2022. Overall, the quality of bowel cleansing was assessed using the Boston Bowel Preparation Scale (BBPS). Results The 4,699 subjects who underwent screening colonoscopy were classified as the non-obese (n = 3,058, 65.1%) and obese (n = 1, 641, 34.9%) groups. The quality of bowel preparation measured by the efficacy of preparation in each segment, overall high-quality cleaning and successful cleansing, and rate of colonoscopy termination due to inadequate preparation were not significantly different between the non-obese and obese groups and according to BMI subgroups. Polyp and adenoma detection rates were significantly higher in the obese group than in the non-obese group after propensity score matching for age and sex, which are well-known risk factors for colorectal neoplasia (60.1% vs 54.1%, p = 0.001 and 39.2% vs 34.6%, p = 0.006, respectively). Conclusions Obesity and BMI were not associated with suboptimal preparation for colonoscopy when low-volume agents were used. In addition, polyp and adenoma detection rates were significantly higher in the obese group than in the non-obese group.