Meta-analysis: One-day Low-residue Diet Achieves Comparable Bowel Cleansing Compared to Multi-day Regimens

Background: Colorectal cancer remains a leading cause of cancer-related morbidity worldwide, making early detection through colonoscopy essential. Adequate bowel preparation is crucial to maximize mucosal visibility and detect lesions effectively. Although low-residue diets (LRDs) are commonly recommended before colonoscopy, guidelines vary regarding the optimal duration (one day versus multiple days). This systematic review and meta-analysis evaluated whether a one-day LRD regimen is non-inferior to multi-day protocols in achieving satisfactory bowel cleansing and lesion detection.

Objective: To compare the efficacy of 1-day versus >1-day LRD regimens for bowel preparation in adult patients undergoing elective colonoscopy, focusing on bowel cleanliness, polyp detection, and adenoma detection rates.

Methods: A comprehensive search of PubMed, Cochrane Central Register of Controlled Trials, ScienceDirect, Scopus, and ClinicalTrials.gov was conducted for randomized controlled trials (RCTs) comparing 1-day with >1-day LRD regimens. Six RCTs involving 2,469 participants met inclusion criteria. Patients were randomized to either a 1-day LRD (n=1,237) or a multi-day LRD (n=1,232). Adequate bowel preparation was primarily defined by a Boston Bowel Preparation Scale (BBPS) score ≥2 in each segment or total BBPS ≥6. Secondary outcomes included polyp detection rate (PDR), adenoma detection rate (ADR), withdrawal time, cecal intubation rate, and cecal intubation time.

Results: Both groups demonstrated similar rates of adequate bowel preparation (87.2% in the 1-day LRD vs. 87.1% in the multi-day group), with no significant difference (OR=1.03, 95% CI, 0.76–1.41; p=0.84; I2=0%). PDR was likewise comparable (OR=0.91, 95% CI, 0.76–1.09; p=0.29; I2=16%), as was ADR (OR=0.87, 95% CI, 0.71–1.08; p=0.21; I2=0%). Withdrawal time did not differ (MD=–0.01 minutes, 95% CI, –0.25 to 0.24; p=0.97; I2=63%), and cecal intubation parameters were also statistically similar. Across studies, the pooled mean global BBPS revealed minimal difference (MD=0.16, 95% CI, –0.02 to 0.34; p=0.08; I2=15%), confirming the non-inferiority of a shorter LRD protocol.

Conclusions: A one-day LRD achieves bowel cleansing outcomes comparable to those of multi-day LRDs, without compromising polyp or adenoma detection. This shorter regimen may help optimize patient adherence, reduce dietary restriction burden, and simplify procedural logistics, especially for busy endoscopy practices.

Implications for Practice: Adopting a 1-day LRD can streamline preparation, improve patient satisfaction, and maintain high-quality visualization. Clinicians should weigh individual patient factors such as chronic constipation or comorbidities but may generally favor a shorter dietary restriction period to enhance compliance and comfort.

Study Strengths and Limitations: This meta-analysis included only RCTs, strengthening its internal validity. Heterogeneity for primary outcomes was minimal. However, the included trials employed varied dietary protocols and bowel preparation solutions. Additionally, some studies lacked uniform reporting of cecal intubation endpoints, limiting direct comparisons. Future investigations with standardized outcome measures could offer more definitive guidance.

Future Research: Further large-scale RCTs should assess cost-effectiveness, patient-reported outcomes, and LRD composition in specific populations. Identifying optimal dietary instructions for individuals with slower colonic transit or specific nutritional needs would refine colonoscopy preparation guidelines and potentially increase detection of precancerous lesions.

Reference: Putri RD, et al. One-day low-residue diet is equally effective as the multiple-day low-residue diet in achieving adequate bowel cleansing: a meta-analysis of randomized controlled trials. Clinical Endoscopy. 2024. DOI: https://doi.org/10.5946/ce.2024.061