Comparing low volume versus intermediate volume bowel preparation and their impact on work and tolerability: an open-label, noninferiority randomized controlled trial

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 their impact on tolerability, health-related quality of life (HRQoL), and work.We conducted an open-label, noninferiority randomized trial in four Dutch hospitals. Patients were randomized to 2 L polyethylene glycol with ascorbate (2L PEG+Asc) or 1 L with added sodium sulfate (1L PEG+Asc). Before and after preparation, patients completed validated questionnaires on productivity, tolerability, and HRQoL. The primary outcome was the proportion of patients with adequate bowel preparation, aiming to demonstrate noninferiority of 1L PEG+Asc vs. 2L PEG+Asc (5% noninferiority margin). Secondary outcomes included willingness to repeat, with exploratory analysis of associated factors using multivariable logistic regression, change in HRQoL scores, tolerability, and work-related impact.We included 467 patients (2L PEG+Asc, n = 229; 1L PEG+Asc, n = 238). 1L PEG+Asc was noninferior to 2L: adequate cleansing rate, 96.1% (95%CI 92.6% to 98.0%) vs. 96.4% (95%CI 93.0% to 98.3%; <i>P</i> = 0.84; Δ -0.4, 95%CI -4.0 to 3.3). More patients in the 1L PEG+Asc group were willing to repeat the preparation (59.9% vs. 48.3%; <i>P</i> = 0.04), with tolerability the most influential factor (odds ratios 0.05 and 0.22 for difficult or fair vs. good tolerability, adjusted for symptoms, satisfaction, and 1L/2L PEG+Asc). No clinically relevant changes in HRQoL were observed. Absenteeism and impaired work productivity occurred in 7.9% and 12.3%, respectively, with no between-group differences.Bowel preparation with 1L PEG+Asc is noninferior to 2L PEG+Asc and associated with higher willingness to repeat. Tolerability is fundamental for effective cleansing and reducing colonoscopy barriers.