S397 Lactulose vs Polyethylene Glycol for Colonoscopy Bowel Preparation: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Introduction: Effective colonoscopy depends on successful bowel preparation. Polyethylene glycol (PEG) solutions are the standard regimens, but they are often poorly tolerated due to their taste and large volume. Lactulose, an osmotic laxative primarily used to treat constipation, has emerged as a more palatable, lower-volume alternative for bowel preparation. Studies to date comparing these 2 regimens have yielded variable and sometimes conflicting results. In this systematic review and meta-analysis, we aimed to compare lactulose- and PEG-based regimens in terms of bowel cleansing efficacy and adverse events. Methods: We conducted a systematic literature search in PubMed, Embase, and Cochrane databases through May 2025 to identify randomized controlled trials (RCTs) comparing lactulose- and PEG-based bowel preparation regimens for colonoscopy in adults that reported at least one outcome of interest. The primary outcome was the bowel cleansing efficacy; secondary outcomes were polyp detection rate and adverse events. The mean difference (MD) and risk ratio (RR) were used as effect measures for continuous and dichotomous outcomes, respectively. Pooled analyses were performed using random-effects models. Results: Six RCTs encompassing 1,447 patients (54.2% female; mean age 51.7 years) were included. Baseline characteristics were similar between the 2 regimens across all studies. Adequate bowel preparation rates were similar between the lactulose and PEG groups (RR 1.01, 95% confidence interval [CI] 0.97–1.06). Lactulose was associated with modestly higher total Boston Bowel Preparation Scale (BBPS) scores (MD 0.48, 95% CI 0.03–0.92) and transverse colon BBPS scores (MD 0.11, 95% CI 0.04–0.24), whereas differences in right colon (MD 0.25, 95% CI -0.01–0.52) and left colon BBPS scores (MD 0.02, 95% CI -0.30–0.34) did not reach statistical significance. Polyp detection rates did not differ significantly (RR 1.11, 95% CI 0.81–1.51). Adverse event rates, including nausea or vomiting (RR 0.79, 95% CI 0.33–1.89), abdominal bloating (RR 0.33, 95% CI 0.05–2.22), and abdominal pain (RR 0.90, 95% CI 0.11–7.46), were also comparable. Conclusion: Lactulose demonstrated comparable efficacy to PEG in achieving adequate bowel preparation, with slightly higher overall and segmental BBPS scores in some regions. Polyp detection and adverse event rates were similar between the 2 regimens. These findings suggest that lactulose may serve as an alternative to PEG.