Safety, Patient’s Tolerance, and Efficacy of a 2-Liter Vitamin C-Enriched Macrogol Bowel Preparation: A Randomized, Endoscopist-Blinded Prospective Comparison With a 4-Liter Macrogol Solution

BACKGROUND:Optimal bowel preparation is associated with lower polyp miss rates, but patients have difficulties in complying with the usual 4-L bowel preparation. OBJECTIVE:This study aimed to compare the safety, acceptance, and efficacy of 2-L polyethylene glycol electrolyte solution enriched in vitamin C with 4-L polyethylene glycol electrolyte solution. DESIGN:This study is an endoscopist-blinded randomized controlled trial. SETTINGS:The study was conducted at a tertiary referral hospital. PATIENTS:Consecutive outpatients were randomly assigned to receive 4-L polyethylene glycol electrolyte solution or 2-L polyethylene glycol electrolyte solution enriched in vitamin C with 2 L of clear fluids in a single-dose or a split-dose regime. MAIN OUTCOME MEASURES:Safety was assessed by blood sampling before and after the preparation and by a 30-day postcolonoscopy chart and complication database review. Acceptance was investigated by questionnaires, and the adequacy of bowel preparation was assessed by the Aronchick and Ottawa scales. RESULTS:One hundred eighty-eight patients, 98 in the polyethylene glycol electrolyte solution enriched in vitamin C group and 90 in the polyethylene glycol electrolyte solution group, participated. Although changes in bicarbonate blood concentrations with polyethylene glycol electrolyte solution enriched in vitamin C were seen to such an extent that the blinded investigator correctly guessed the preparation in 75.6%, no unsafe values were observed. A 30-day chart and complication database review revealed 1 severe adverse event of a myocardial infarction in the polyethylene glycol electrolyte solution enriched in vitamin C group. Patient acceptance and compliance were significantly higher with the polyethylene glycol electrolyte solution enriched in vitamin C group. The impact on sleep, daily activities, and physical complaints were similar in both groups. Polyethylene glycol electrolyte solution enriched in vitamin C was noninferior to polyethylene glycol electrolyte solution in cleansing efficacy, but the segmental rating of excellent and good preparation in right and transverse colon was significantly better for polyethylene glycol electrolyte solution, especially when taken as a split dose. LIMITATIONS:The results cannot be extrapolated to immobile inpatients with comorbidities. Another limitation of our study was the inability to determine plasma vitamin C concentrations and to assess the quality of colonoscopy performance. CONC