A Comparison of Sodium Phosphosoda Purgative to Polyethylene Glycol Bowel Preparations Prior to Colonoscopy

Background and Objectives: Successful colonoscopy is contingent upon adequate bowel preparation, which is often achieved using either an oral sodium phosphate preparation or a polyethylene glycol-based preparation. Comparison of the relative performance of these two classes of agents has been assessed only in the context of clinical trials (and with mixed findings). However, efficacy measured in clinical trials often is not reflective of effectiveness in clinical practice. We undertook this analysis to determine the relative clinical effectiveness of oral sodium phosphosoda versus polyethylene glycol in clinical practice. Methods: Subjects (n=343) were selected from among patients receiving outpatient colonoscopy at our institution between January 2004 and February 2006. Demographic, biochemical, and comorbid disease data were abstracted from the electronic medical record. Colonoscopy preparation, indication, and preparation quality were abstracted from colonoscopy reports. Results: As compared to subjects receiving polyethylene glycol, those receiving oral sodium phosphosoda had an adjusted odds ratio (OR) (95% confidence intervals [CIs]) for adequate/good/excellent bowel preparation quality of 2.23 (1.18 4.22) and on adjusted OR (95% CIs) for good/excellent bowel preparation of 2.24 (1.26-3.97). There was no interaction on the basis of colonoscopy indication. Conclusions: Oral sodium phosphate-based purgatives were associated with significantly better bowel preparation quality among outpatients at our center.