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.

Risk factors for inadequate bowel preparation in patients using high- and low-volume cleansing products

“…LV products, either PEG- or non-PEG-based, have been introduced in order to improve patients’ acceptability and have been proven equally effective in randomized clinical trials [17–19]. We have confirmed these results in the present study population in a previous paper [15].…”

“…Incomplete assumption of the cleansing product (<75% of the prescribed dose of PEG) was more common among patients who used HV preparations (7.9% vs. 5.4%; P = 0.00318), whereas there was no difference in adherence to the low-fibre diet (10.5% vs. 11.9%; P = 0.3287). Overall, adequate bowel preparation was achieved in 87.6% of patients; as already shown in our previous study [15], there were no differences in efficacy between HV and LV preparations, either overall (89.2% vs. 86.6%; P = 0.0983) or considering the use of split or day-before regimens.…”

“…Incomplete assumption was, as expected, more common among patients who used HV preparation in our cohort. We have previously reported in the same study population [15] that the occurrence of vomiting and nausea (but not abdominal pain or bloating) is related to incomplete assumption, confirming that increasing palatability of cleansing products is a pivotal strategy to increase adherence, independently from volume of preparation.…”

“…Analysis of clinical outcomes (such as polyp and ADRs) and of patients’ self-reported tolerability were outside the purposes of the current study because they were already addressed in a previous study [15].…”