Importance of bowel habits as a risk factor of inadequate bowel preparation in colonoscopy

Background: Inadequate bowel preparation (IBP) negatively affects the quality of colonoscopy. Although constipation has been reported as one of the most important predictors of IBP, there is limited information about the relation of IBP to bowel habit factors. We aimed to investigate predictors of IBP focusing on symptoms, medications, and severity of constipation. Methods: This was a questionnaire-based prospective observational study, and 1157 consecutive outpatients underwent colonoscopy. Chronic constipation was diagnosed by ROME 4 criteria, which includes questions regarding constipation-related symptoms. Severity of constipation was scored by Constipation Scoring System (CSS). Results: A total 1049 patients were included. At multivariate analysis, age, chronic constipation, and diabetes mellitus were independent risk factors for IBP. IBP increased with CSS score (P for trend=0.01). Among constipation-related symptoms, straining during defecations was a significant predictor of IBP (OR=1.62). Furthermore, chronic use of stimulant laxatives is an independent predictor of IBP (OR=2.57). Conclusions: Chronic constipation was a risk factor of IBP, as expected. The risk of IBP increased with the severity of constipation. Straining and chronic use of stimulant laxatives were significant predictor of IBP. For severe constipated patients with straining and chronic use of stimulant laxatives, an intensified preparation regimen should be especially considered.