Obesity Predicts Inadequate Bowel Preparation At Colonoscopy, Study Finds

Obesity has become an epidemic in the present era, both in the U.S. and in other developed nations. Abnormal elevation of body mass index (BMI) is associated with several gastrointestinal diagnoses, including diverticular disease, gastroesophageal reflux disease, colon polyps and colon cancer.

Since the majority of colon cancers arise from adenomatous (benign) colon polyps, proper screening becomes crucial while performing colonoscopy on obese patients. An inadequately cleansed colon can jeopardize the effectiveness of screening or surveillance colonoscopy, exposing these patients at higher risk for colorectal tumors to the dangers of missed lesions and higher cost of repeat colonoscopy.

"The implications of our findings are profound. Since over a quarter of all patients had an inadequate examination, identification of a patient profile with a high risk for poor colon preparation will be helpful in capturing those who would benefit from an initial individualized designer preparation regimen," said Brian Borg, MD, of Washington University in St. Louis, MO and lead author of the study. "Our results suggest that the obese patient should at least be subject to more precise instructions and possibly a more rigorous bowel preparation regimen. In addition, as the number of risk factors for an inadequate bowel preparation increase, the need for early repeat colonoscopy escalates."

In this study, believed to be the first of its kind, patients were designated overweight when BMI was ≥25 and obese when ≥30. All colonoscopy procedures performed at a tertiary referral center over a four-month period were evaluated. Bowel preparation was assigned a unique composite outcome score that took into account a subjective bowel preparation score, earlier recommendation for follow-up colonoscopy due to inadequate bowel preparation and the endoscopist's confidence in adequate evaluation of the colon. Univariate and multivariate logistic regression analyses were performed to identify the role of BMI in predicting an inadequate bowel preparation.

During the study period, 1,588 patients fulfilled inclusion criteria. An abnormal BMI (≥25) was associated with an inadequate composite outcome score. In multivariate logistic regression analyses, both BMI ≥25 and ≥30 were retained as independent predictors of inadequate bowel preparation. Each unit increase in BMI increased the likelihood of an inadequate composite outcome score by 2.1 percent. Additional independent predictors of inadequate preparation exponentially increased the likelihood of an inadequate composite outcome score; seven additional risk factors identified 97.5 percent of overweight patients with an inadequate composite outcome score.