Efficacy and Tolerability of High and Low-volume Bowel Preparation Compared: a Real-life Single-blinded Large-population Study

Abstract Background: Low-volume (LV) preparations for colonoscopy have shown similar efficacy compared to high-volume (HV) ones in trials. However, real-life clinical outcomes data are lacking. Our aim was to assess patients’ free choice among HV preparations (4L polyethylene glycol, PEG) and LV (2L PEG plus bisacodyl) and to compare efficacy and tolerability. Methods: Consecutive outpatients referred for colonoscopy could choose either LV or HV preparation with schedules (day-before or split-dose) depending on their appointment time. Adequate bowel preparation according to Boston Bowel Preparation Scale, clinical outcomes and self-reported tolerability of HV and LV were blindly assessed.Results: 2,040 patients were enrolled and 1,815 (age 60.6 years, 50.2% men) finally included. LV was chosen by 52% of patients (50.8% of men, 54.9% of women). Split-dose schedule was more common with HV (44.7% vs. 38.2%, p=0.0055). HV and LV preparations showed similar adequate bowel preparation rates (89.2% vs. 86.6%, p=0.0983) but HV ones resulted higher in detection rates for polyps (PDR; OR 1.30, 95% CI 1.03–1.64, p=0.0254), adenomas (ADR; OR 1.28, 95% CI 0.99–1.65, p=0.0519) and advanced adenomas (AADR; OR 1.54, 95% CI 0.96–2.46, p= 0.0723) after adjustment for sex, age, indications. Visual Analogue Scale tolerability scored equally (7 [5-9]) but a ≥75% dose intake was more frequent with LV.Conclusions: in a real-life setting, LV preparation confirms similar efficacy and tolerability compared to HV. However, with higher PDR and a trend toward higher ADR and AADR, HV should still be considered the reference standard for clinical trials.