A Randomized Prospective Trial Comparing Different Regimens of Oral Sodium Phosphate and Polyethylene Glycol Solution for Colonoscopy Preparation

Abstract

Background: Recent FDA and Health Canada statements warned physicians regarding the risk of electrolyte abnormalities if more than 45 ml of oral sodium phosphate solution was used in a 24-hour period in patients with or without risk factors. The purpose of this study was to compare the tolerability, safety and cleansing ability of different regimens of oral sodium phosphate fleet as well as a polyethylene glycol-based preparation (PEG) in healthy patients. Methods: One hundred patients undergoing routine colonoscopy were randomized to one of four purgative methods: 2 bottles of oral sodium phosphate solution; 6 hours apart (Group 1), 12 hours apart (Group 2), 24 hours apart (Group 3), and 4 L of PEG solution (Group 4). Bowel preparation, patient satisfaction and electrolyte imbalances were the measured endpoints. Continuous measures were analyzed using ANOVA and categorical measures were assessed using chi-square tests. Corrections for multiple comparisons were undertaken. Results: Overall bowel preparation quality did not differ between groups although a trend favoring Group 2 was observed. The PEG group had significantly more colonic fluid than the other groups (p=0.01). The quality was consistently worse in the right colon for all groups (p=0.74). There was no difference in overall satisfaction with the regimens although Group 3 missed significantly more days of work (p=0.015). Tolerability was not different among groups and no clinically significant adverse events were identified. The three oral sodium phosphate groups were independently associated with a greater rise in serum phosphate than seen with the PEG group (p< 0.001). There were no differences in the increase in phosphate among the three sodium phosphate groups. There was no difference in the decrease in calcium among all groups. The three sodium phosphate groups were associated with a greater decrease in potassium than the PEG group (p=0.002) but no significant difference was noted among sodium phosphate groups. Conclusion: The PEG group had more colonic fluid at colonoscopy but was associated with less electrolyte changes than each of the oral sodium phosphate groups. In comparing the 3 sodium phosphate groups, the overall cleansing ability was similar with a trend favoring Group 2, there were no significant differences in electrolyte changes and Group 3 required more time off work. This study is ongoing.