Predictors of Suboptimal Bowel Preparation Using 3-l of Polyethylene Glycol for an Outpatient Colonoscopy: A Prospective Observational Study

Background: A 3-l polyethylene glycol (PEG) solution provided better bowel cleansing quality than a 2-l solution for outpatient colonoscopy. Predictors of suboptimal preparation using a 3-l PEG have not been previously reported. Aims: To investigate the possible predictors of suboptimal bowel preparation using 3-l of PEG. Methods: We analyzed a database of 1404 consecutive colonoscopies during a 27-month period at a community hospital. A split-dose PEG regimen was provided for morning colonoscopies, and a same-day PEG regimen was provided for afternoon colonoscopies. The level of bowel cleansing was prospectively scored according to the Boston Bowel Preparation Scale (BBPS). Possible predictors of suboptimal colon preparation, defined as a BBPS score <7, were analyzed using univariate statistics and multivariate logistic regression models. Results: The mean age of the study population (46.7 % men) was 52.5 years (range 20–80 years, SD 11.1 years), and the majority of patients (77.6 %) underwent morning colonoscopies. A suboptimal bowel preparation was reported in 17.2 % of the observed colonoscopies. In the multivariate regression analysis, constipation (odds ratio [OR] 1.60, 95 % confidence interval [CI] 1.15–2.22), male gender (OR 1.68, 95 % CI 1.25–2.25), obesity (OR 1.76, 95 % CI 1.29–2.41), and inadequate (<80 %) PEG consumption (OR 5.4, 95 % CI 2.67–10.89) were independent predictors of a suboptimal colon preparation. Conclusions: This prospective study identified that constipation, male gender, obesity, and inadequate intake of PEG were significant risk factors for suboptimal bowel preparation using a 3-l PEG solution for outpatient colonoscopy. Interventions of optimized colonoscopy preparation should be targeted at these patient populations.