Impact of low-residue diet on bowel preparation for colonoscopy

BACKGROUND: Few studies have focused on the effect of dietary residue on preparation for colonoscopy. OBJECTIVE: To determine the impact of a low-residue diet on the quality of bowel preparation. SETTING: Chang Gung Memorial Hospital, Kaohsiung Medical Center, Taiwan. PATIENTS: Eight hundred four consecutive patients (50.4 ± 11.6 y (range, 18-88 y), 43.6% female) undergoing colonoscopy between May 2008 and June 2009. INTERVENTION: Subjects were advised to consume a lowresidue diet for 2 days before the procedure, and they recorded food intake by use of diet diaries. MAIN OUTCOME MEASURES: The quality of bowel cleansing was evaluated using the Ottawa bowel preparation scale. Patient variables and details of each procedure were recorded, and factors that determined the quality of colon cleansing were determined. LIMITATIONS: Categories of foods consumed were recorded, but not the amount eaten, and diet diaries were completed retrospectively. RESULTS: Data from 789 patients were analyzed. Only 44.2% of patients adhered to a low-residue diet, and 39.3% of patients were inadequately prepared. On multivariate logistic regression analysis, age (P =.007), body mass index (P =.01), abdominal girth (P =.041), bowel habit tending to constipation (P =.015), and high-residue diet (P <.0001) were independent predictors of inadequate bowel preparation. There was a linear relationship between dietary residue score and bowel cleanliness score (r = -0.475; P <.001). CONCLUSIONS: A low-residue diet for 2 days of before colonoscopy improves bowel cleansing, but compliance with this advice is poor. The importance of a low-residue diet should be emphasized to patients undergoing preparation for colonoscopy.