Comparing low-volume vs. intermediate volume bowel preparation and its impact on work and tolerability: An open-label, non-inferiority, randomized controlled trial

Background: Bowel preparation is essential for colonoscopy but may deter patients. Although low-volume laxatives are better tolerated, their impact on patient-reported outcomes remains unclear. We compared low- and intermediate volume bowel preparation and assessed the impact on tolerability, health-related quality of life (HRQoL) and work. Methods: We conducted an open-label, non-inferiority, randomized trial in four Dutch hospitals. Patients were randomized to 2L polyethylene glycol with ascorbate (2LPEG+Asc) or 1LPEG+Asc with sodium sulfate. Before and after preparation, patients completed validated questionnaires on productivity, tolerability, and HRQoL. Primary outcome was the proportion of patients with adequate bowel preparation, aiming to demonstrate non-inferiority of 1LPEG+Asc to 2L (5% non-inferiority margin). Secondary outcomes included willingness-to-repeat, with exploratory analysis of associated factors using multivariable logistic regression, change in QoL scores, tolerability, and work-related impact. Results: We included 467 patients (2LPEG+Asc: n=229,1L PEG+Asc: n=238). 1L PEG+Asc was non-inferior to 2L PEG+Asc;adequate cleansing rates were 96.1% (95%CI 92.6-98.0%) vs. 96.4% (95%CI 92.9-98.3%) (p=0.84; Δ -0.4, 95%CI -4.0–3.3). More patients in the 1L PEG+Asc group were willing to repeat the preparation (59.9% vs 48.3%, p=0.04), with tolerability as the most influential factor (OR=0.05 and OR=0.22 for difficult or fair vs. good tolerability, adjusted for symptoms, satisfaction, and 1LPEG+Asc/2LPEG+Asc). No clinically relevant changes in HRQoL were observed. Absenteeism and impaired working productivity occurred in 7.9% and 12.3%, respectively, with no between-group differences. Conclusions: Bowel preparation with 1L PEG+Asc is non-inferior to 2L PEG+Asc and has a higher willingness-to-repeat. Tolerability is fundamental for effective cleansing and reducing colonoscopy barriers.