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

Article information

Clin Endosc. 2025;58(1):63-76

Publication date (electronic) : 2024 December 12

doi : https://doi.org/10.5946/ce.2024.061

Raeni Dwi Putri^,1, Fiki Amalia¹, Festy Aldina Utami¹, Yunisa Pamela^,2, Mas Rizky A.A. Syamsunarno²

¹Faculty of Medicine, University of Padjadjaran, Bandung, Indonesia

²Department of Biomedical Sciences, Faculty of Medicine, University of Padjadjaran, Bandung, Indonesia

Correspondence: Yunisa Pamela Department of Biomedical Sciences, Faculty of Medicine, University of Padjadjaran, Prof. Eyckman Street No.38, Pasteur, Sukajadi, Bandung, West Java 40161, Indonesia E-mail: yunisa.pamela@unpad.ac.id

Correspondence: Raeni Dwi Putri Faculty of Medicine, University of Padjadjaran, Bandung, 40161 West Java, Indonesia E-mail: reraeni@gmail.com

Received 2024 March 11; Revised 2024 July 24; Accepted 2024 August 8.

Abstract

Graphical abstract

INTRODUCTION

Colonoscopy is a widely utilized diagnostic and preventive procedure for colorectal diseases, including colorectal cancer, which is a leading cause of cancer-related morbidity and mortality worldwide.1 Successful colonoscopy outcomes are contingent upon effective bowel preparation, a crucial pre-procedural step to achieve optimal visualization of the colonic mucosa.2,3 Suboptimal intestinal cleansing compromises the effectiveness of colonoscopy and diminishes the adenoma detection rate (ADR), prolongs the procedure time, and undermines patient compliance. Additionally, it increases the risk of adverse events and contributes to overall increased costs.4-6 The primary factors affecting the quality of colon cleansing include inadequate adherence to or limited tolerance of bowel preparation, ineffectiveness of the cleansing protocol encompassing both diet and cleansing solutions, the time gap between the last dose of bowel preparation and colonoscopy, and the method of administration (full- or split-dose regimens).3,7-9

The low-residue diet (LRD), a dietary regimen restricting high-fiber food consumption, has demonstrated a higher level of tolerability than the traditionally recommended clear liquid diet (CLD).10-12 The most recent guidelines advocate using LRD with an evidence level at least equivalent to that of CLD.13,14 Although the guidelines from The European Society of Gastrointestinal Endoscopy (ESGE) assert a lack of evidence supporting LRD use for more than 24 hours,13 they acknowledge that certain endoscopists recommend an extended duration, such as 2 or 3 days, of an LRD before colonoscopy. However, the recommended duration for LRD is notably varied, as clinical practice supports both 1-day and more than 1-day protocols.

The debate surrounding the optimal LRD duration for bowel preparation remains an area of active investigation, with implications for patient compliance and procedural efficacy.15-17 Given the potential impact on patient experience and adherence, this systematic review and meta-analysis aimed to synthesize and critically appraise the available randomized controlled trials (RCTs) comparing the efficacy of 1-day versus >1-day LRD in bowel preparation before colonoscopy. We intend to provide a robust evidence base for clinicians, researchers, and healthcare policymakers to inform decision-making and guideline the development in colonoscopy preparation by systematically analyzing the existing literature.

METHODS

Data sources and search strategy

We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to conduct this meta-analysis. The meta-analysis protocol was registered with PROSPERO on November 11th, 2023 (PROSPERO ID: CRD42023477314). Three authors (RDP, FA, and FAU) performed extensive searches across multiple databases, including PubMed, Cochrane Central Register of Controlled Trials, ScienceDirect, Scopus, and ClinicalTrials.gov, from the inception of the databases until October 2023, and May 2024 as the manuscript was reviewed. The search was restricted to English-language articles using both abbreviated and expanded keywords, which included terms such as “low residue diet” and “colonoscopy” (Supplementary Table 1). In addition to the database searches, manual search of references in the included studies was conducted, eliminating duplicate citations. The titles and abstracts of the retrieved articles were independently assessed using the RDP and FA. Disagreements were resolved through discussions with the FAU. The full texts of the remaining articles were carefully examined. The screening results are presented in Figure 1, which shows the PRISMA flowchart.

Fig. 1.

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram of study screening and selection.

RESULTS

As illustrated in Figure 1, 316 of the 533 search results were duplicate records. A total of 210 articles were deemed unrelated based on title or abstract review and consequently excluded. The remaining seven articles underwent a thorough screening process. Two other articles were identified through a citation search. After applying the inclusion and exclusion criteria, six RCTs were included. The reasons for excluding certain studies were overlapping studies (n=1), different types of interventions (n=1), and different types of articles (n=1). The primary characteristics of the included studies are presented in Tables 1-3.19-24

Table 1.

Characteristics of studies

Table 2.

Comparison of LRD preparations, bowel solutions, and colonoscopy indications

Table 3.

Outcomes of 1-day vs. >1-day LRD on bowel preparation quality and detection rates in colonoscopy

Of the 2,469 participants from the six RCTs19-23 included in this study, 1,238 (50.1%) were males. Among these participants, 1,237 (50.1%) were randomized to undergo a 1-day LRD, while the remaining 1,232 subjects had >1-day LRD (49.9%). Five studies compared 1-day and 3-day LRD, and one study compared 1-day and 2-day LRD. One study employed a noninferiority model. Table 1 provides the definition of adequate bowel preparation as specified in each study.

Mucosal visualization

The rates of adequate bowel preparation for 1 day and >1-day are 87.2% and 87.1%, respectively. The difference in the pooled rate of adequate bowel preparation at 1 day and > 1 day yielded an OR of 1.03, p=0.84, I²=0%, indicating a statistically nonsignificant difference (Fig. 2A). The mean global BBPS between the two groups is not significant; MD 0.16 (95% CI, –0.02 to 0.34; p=0.08; I²=15%; Fig. 2B).

Fig. 2.

(A) Comparison of adequate bowel preparation rate between 1-day and 3-day low-residue diet (LRD) group. (B) Comparison of mean Boston bowel preparation scale between 1-day and 3-day LRD group. M-H, Mantel–Haenszel; CI, confidence interval.

Secondary outcomes

No statistically significant differences were found between the groups in the PDR (OR, 0.91; 95% CI, 0.76–1.09; p=0.29; I²=16%; Fig. 3A); ADR (OR, 0.87; 95% CI, 0.71–1.08; p=0.21; I²=0%; Fig. 3B); withdrawal time (MD, –0.01; 95% CI, –0.25 to 0.24; p=0.97; I²=63%; Fig. 3C); cecal intubation rate (OR, 1.35; 95% CI, 0.73–2.50; p=0.34; I²=42%; Fig. 3D); and cecal intubation time (MD, –0.07; 95% CI, –0.38 to 0.24; p=0.67; I²=0%; Fig. 3E).

Fig. 3.

Comparison between 1-day and 3-day low-residue diet (LRD) group in polyp detection rate (A), adenoma detection rate (B), withdrawal time (C), cecal intubation rate (D), and cecal intubation time (E). M-H, Mantel–Haenszel; CI, confidence interval.

Risk of bias

Figure 4 presents an overview of the separate assessments conducted for each RCT included in the meta-analysis. Among these, three studies were categorized as having a low risk of bias, one study had some concerns, and two exhibited a high risk of bias. Two studies categorized as high risk of selection bias reported results from multiple eligible analyses of the data. The funnel plots did not show conclusive evidence of publication bias; however, the analysis was constrained by the limited number of studies (<10; Fig. 5).

Fig. 4.

Risk of bias assessment of the included studies in the meta-analysis using Cochrane Risk-of-Bias 2 tool.

Fig. 5.

(A) Funnel plot for Boston bowel preparation scale of the included studies. (B) Funnel plot for polyp detection rate of the included studies.

DISCUSSION

Effective bowel cleansing is crucial in various aspects of colonoscopy. Inadequate bowel cleansing diminishes the quality of colonoscopy and has detrimental effects on the ADR, procedure duration, and patient compliance. Furthermore, it increases the risk of adverse events and contributes to overall procedural costs.4-6 A prospective study investigating repeated colonoscopies revealed that the likelihood of missing adenomas larger than 5 mm was three times higher in cases of inadequate intestinal preparation.25

Certain scholars suggest a three-day LRD before colonoscopy because of the prolonged transit time observed in certain patients, while other scholars advocate for a one-day LRD. The ESGE guidelines recommends a one-day LRD for bowel preparation based on practical experience, albeit without robust evidence from evidence-based studies.13 A systematic review and meta-analysis encompassing six RCTs encompassing 2,469 patients comparing 1-day and >1-day LRD for individuals scheduled for colonoscopy revealed the following key findings: (1) differences between the two groups concerning adequate bowel preparation are not significant, as assessed by mucosal visualization using the BBPS, and (2) the rates of polyp and adenoma detection are not significantly different between the 1-day and >1-day LRD groups.

All included studies applied blinding to the gastroenterologists. The patients were instructed not to reveal their diet to the gastroenterologist team. Regarding adequate bowel preparation, four articles included in this study used categorical data and four articles used numerical data to assess BBPS in the 1-day vs. >1-day LRD group comparisons. Our findings suggest that a more convenient 1-day LRD regimen may offer a practical alternative to the >1-day regimen without compromising bowel cleanliness. The nonsuperiority test conducted by Machlab et al.22 in their study revealed that the 1-day LRD group exhibited superior rates of excellent colon cleansing. An RCT comparing 1-day vs. 2-day LRD showed that both groups exhibited similar bowel preparation qualities and demonstrated comparable colonoscope insertion times, withdrawal times, PDRs, and patient tolerance scores (hanger comfort scores).24

While it might seem logical that bowel cleansing would improve with an extended period of fiber abstinence, some authors have argued otherwise. They argued that LRD may decrease bowel motility and extend the time taken for substances to move through the intestines. This counterintuitive effect could be particularly pronounced in individuals dealing with constipation, leading to outcomes opposite to those desired in terms of effective bowel preparation.11 The movement of material through the colon, known as colonic transit, is affected by dietary fiber. Specifically, insoluble fiber promotes faster colonic transit through mechanical and neuroendocrine mechanisms.26,27 Consequently, it is plausible to hypothesize that diminishing this influence could result in a reduction in colon transit.21 Although lacking a standardized definition; consensus among some authors defines LRD as a fiber intake of less than 10 g/day.26,28 Our analysis revealed comparable rates of polyp and adenoma detection between the 1-day and >1-day LRD groups, implying that the choice of dietary preparation duration may not significantly impact the efficacy of colonoscopy in detecting colonic abnormalities.

Regarding clinical implications, the observed lack of significant differences in bowel preparation and detection rates supports the consideration of a shorter, equally effective, 1-day LRD, potentially enhancing patient adherence and satisfaction. Patient preference and satisfaction have emerged as important considerations. Gimeno-García et al.19 highlighted that subjects showed a preference for 1-day LRD based on satisfaction and perceived difficulty. Jiao et al.’s study20 corroborated this finding, noting that subjects favored 1-day LRD because of its shorter duration and easier compliance. Taveira et al.’s findings21 add depth to this aspect, suggesting a higher perceived difficulty in adhering to the 3-day diet, favoring the recommendation of a 1-day LRD. The importance of the bowel preparation solution and regimen likely outweighs that of the diet. A shorter diet is not only easier to adhere and more tolerable but also enhances adherence and motivation to the preparation solution and regimen. This brief dietary period underscores the importance of the cleansing solution. Moreover, prolonged LRD may decrease intestinal motility and transit time, potentially exacerbating bowel cleansing issues.22,29 An observational study discovered that the diet consumed on the preceding day of colonoscopy notably impact BBPS scores. The study assessing the diet three days before the colonoscopy suggested that providing multi-day dietary instructions could be perplexing for patients and may not contribute significantly to the effectiveness of bowel preparation results.30

This meta-analysis had several strengths. First, this study only included RCTs, which markedly elevated the evidence credibility. Second, the inclusion of RCTs from diverse countries that utilized consistent intestinal preparations within the same study fostered comparability. Simultaneously, different bowel preparations usage across various studies suggests that the findings of this study can be generalized to other bowel preparation methods. Lastly, the heterogeneity was absent in the assessment of bowel preparation adequacy and ADR outcomes, and heterogeneity was low for the PDR outcome.

Nevertheless, this study had inherent limitations. First, the LRD varied across studies, as each study implemented a distinct plan or protocol devised by the respective nutritionists. Second, there was a divergence in the arrangement of meals among studies; while most permitted all three meals of the LRD, Garcia deviated by utilizing a CLD for dinner.19 Third, certain outcomes were constrained in terms of available data; for instance, only three studies assessed ADR, and two studies evaluated cecal intubation rate and time. However, it is important to highlight that these studies represent all existing research on this subject till now. Lastly, the impact of factors affecting bowel preparation quality, such as patients’ underlying diseases, notably constipation, coupled with challenges in their correction, represents a limitation of this study.

In conclusion, this study revealed no substantial distinction in terms of adequate bowel preparation between the 1-day and >1-day LRD groups as evaluated through mucosal visualization using the BBPS. Additionally, the rates of polyp and adenoma detection did not significantly differ between the two dietary preparation durations. These findings collectively underscore the comparable efficacy of the 1-day and >1-day LRD protocols in achieving satisfactory bowel preparation and highlighting their similar impact on the detection of polyps and adenomas during colonoscopy.

Future research should delve into the cost-effectiveness and patient-reported outcomes associated with different durations of LRD during colonoscopy preparation. Owing to the diverse types and protocols of LRD, further research is necessary in each country. Our study contributes to the growing body of evidence that informs clinical guidelines and suggests potential modifications to existing recommendations. As the field evolves, a comprehensive understanding of the nuances of dietary preparation duration will ultimately contribute to more tailored and patient-centric approaches for colonoscopy procedures.

Supplementary Material

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