Surgery – PICO #3

Brief description of patient problem/setting (summarize the case very briefly)

While talking to a patient prior to her colonoscopy she mentions she has heard that she needs to be on an all-clear liquid diet before her colonoscopy. She has read online that people have been taking a low residue diet to much success over a clear liquid diet and wonders if a low residue diet might be a better alternative for her.

Search Question: Clearly state the question (including outcomes or criteria to be tracked)

Does implementing a low residue diet over a clear liquid diet prior to a colonoscopy show improved bowel preparation and patient tolerance?

Question Type: What kind of question is this? (boxes now checkable in Word)

☐Prevalence                             ☐Screening                  ☐Diagnosis

☐Prognosis                              ☐Treatment                 ☒Harms

Assuming that the highest level of evidence to answer your question will be meta-analysis or systematic review, what other types of study might you include if these are not available (or if there is a much more current study of another type)? Please explain your choices.

– If meta-analysis or systematic review are not available, randomized controlled clinical trials will also offer great supporting evidence as they are carefully planned experiments, reduce the potential for bias, and allow for comparison between intervention and control groups.

– Cohort studies could also be used since they allow to follow the patients who have already received a particular treatment forward over time. This is not as reliable as randomized controlled clinical trials since patients might differ in ways other than in the variable that is being observed.

PICO search terms:

Patients undergoing colonoscopiesLow residue dietClear liquid dietPatient tolerance
Colonoscopy  Improved bowel preparation

Search tools and strategy used:

Please indicate what data bases/tools you used, provide a list of the terms you searched together in each tool, and how many articles were returned using those terms and filters.
Explain how you narrow your choices to the few selected articles.

Results found:

TRIP Database

  • Colonoscopy AND Low Residue Diet AND Clear Liquid Diet – 5


  • Colonoscopy AND Low Residue Diet– 52
  • Colonoscopy AND Low Residue Diet AND Clear Liquid Diet – 19

Google Scholar

  • Colonoscopy AND Low Residue Diet AND Clear Liquid Diet – 19,300
  • Colonoscopy AND Low Residue Diet AND Clear Liquid Diet (last 10 years) – 16,800

Many articles built upon other articles before it, so I tried to use the newest update for the meta-analysis and systematic reviews. There were not too many articles to sift through, but there were enough to use for this PICO. Some articles looked at whether having patients go through three days of a low residue diet versus going through the LR diet the day before had better tolerability and a better colonoscopy overall. I decided against using those articles because they were not pertaining to the clear liquid diet, but it is something that can be looked at in the future. Thankfully, I saw many randomized controlled trials and meta-analysis and systematic reviews that I could use, and did not have to resort to weaker types of studies.

Identify at least 3 articles (or other appropriate reputable sources) that answer your specific question with the highest available level of evidence (you will probably need to look at more than 3 articles to get the 3 most focused and highest-level articles to address your question). Please make sure that they are Medline indexed.

Please post the citation and abstract for each article (to include the journal and authors’ names and date) and say why you chose it.
Please also note what kind of article it is (e.g. meta-analysis, cohort study, or independent blind comparison with gold standard of diagnosis, etc.).

At the bottom of each abstract, please comment on what your key points are from this article (including any points or concepts included in the article, but not present in the abstract – i.e. make the concepts understandable to the reader)

Please note that if the evidence is not in the abstract, you must clearly summarize the evidence in your posting.

Citation: Samarasena, J. B., El Hage Chehade, N., Abadir, A., Yu, A., Tran, E., Mai, D., Thieu, D., Albers, G., Parekh, N. K., Karnes, W. E., Chang, K., & Jamal, M. M. (2022). Single-Day Low-Residue Diet Prior to Colonoscopy Demonstrates Improved Bowel Preparation Quality and Patient Tolerance over Clear Liquid Diet: A Randomized, Single-Blinded, Dual-Center Trial. Digestive Diseases and Sciences, 67(6), 2358–2366.
Type of article: Randomized controlled trial
Abstract   Background and Aims: Patients often refer to bowel preparation and associated dietary restrictions as the greatest deterrents to having a colonoscopy completed or performed. Large studies comparing a low-residue diet (LRD) and a clear liquid diet (CLD) are still limited. The aim of this study is to compare LRD and CLD with regard to bowel preparation quality, tolerance, and satisfaction among a diverse patient population.   Methods: This study is a dual-center, randomized, single-blinded, prospective trial involving adult patients undergoing outpatient colonoscopy at the University of California Irvine Medical Center and an affiliated Veterans Administration hospital. Patients were randomized to consume either a CLD or a planned LRD for the full day prior to colonoscopy. Both groups consumed 4L split-dosed PEG-ELS. The adequacy of bowel preparation was evaluated using the Boston Bowel Preparation Score (BBPS). Adequate preparation was defined as a BBPS ≥ 6 with no individual segment less than a score of 2. Hunger and fatigue pre – and post-procedure were graded on a ten-point scale. Nausea, vomiting, bloating, abdominal cramping, overall discomfort, satisfaction with the diet, willingness to repeat the same preparation and overall experience were assessed.   Results: A total of 195 subjects who underwent colonoscopy from October 2014 to October 2017 were included. The mean BBPS for the LRD and CLD groups was 8.38 and 7.93, respectively (p = 0.1). There was a significantly higher number of adequate preparations in the LRD group compared to CLD (p = 0.05). Evening hunger scores just before starting the bowel preparation were significantly lower in the LRD than the CLD group, 2.81 versus 5.97, respectively (p = 0.006). Subjects in the LRD group showed significantly less nausea (p = 0.047) and bloating (p = 0.04). Symptom scores for vomiting, abdominal cramping, and overall discomfort were similar between the groups. Satisfaction with diet was significantly higher in the LRD group than CLD, 72% versus 37.66%, respectively (p < 0.001). The overall colonoscopy experience and the satisfaction with the preparation itself were also better reported in the LRD group (p < 0.001 and p = 0.002, respectively).   Conclusions: This study, which included a diverse group of patients, demonstrated that patients using a LRD before colonoscopy achieve a bowel preparation quality that is superior to patients on a CLD restriction. This study shows that a low-residue diet improves patient satisfaction and results in significantly better tolerability of bowel preparation. As a less restrictive dietary regimen, the low-residue diet may help improve patient participation in colorectal cancer screening programs.
Key Points: This single-blind randomized control study was comprised of 195 patients who were randomly assigned to either receiving a clear liquid diet or a low residue diet prior to their colonoscopy91 patients were allocated to the clear liquid diet (CLD)104 patients were allocated to the low residue diet (LRD)Patients on the CLD were only allowed to have fruit juices without pulp, carbonated drinks, tea, coffee (with no milk), gelatin products and clear fat-free brothPatients on the LRD were allowed to have eggs, chicken, yogurt, baked potato, white toast and even ice creamThere were no adverse events with either groupBoth groups also had no significant difference in polyp or adenoma detectionParticipants in the LRD group had a higher level of satisfaction with their dietary regimen (72%) versus the participants in the CLD group (37%)The LRD group rated the overall experience better than those in the CLD group (72% vs. 47%)There was significantly less nausea and less bloating that was reported in the LRD group versus the CLD groupSubjects in the LRD group also reported less hunger in the morning after taking the bowel prep overnight versus the CLD groupOverall, the LRD group seemed happier about going through a bowel prep over the CLD group
Why I chose it: I chose this article because it was one of the few articles that included a multi-center trial that looked at a low residue diet versus a clear liquid diet before a colonoscopy. Two healthcare communities with different socioeconomic backgrounds were looked at which increased the generalization of the study. The two groups were relatively equal in its participants.
Citation: Chen, Engeng MDa; Chen, Li MDa; Wang, Fei MDa; Zhang, Wei MDa; Cai, Xianlei MDb; Cao, Gaoyang MDa,∗. Low-residue versus clear liquid diet before colonoscopy: An updated meta-analysis of randomized, controlled trials. Medicine 99(49):p e23541, December 4, 2020. | DOI: 10.1097/MD.0000000000023541
Type of article: Meta-analysis
Abstract: Great value in the early identification and treatment of adenomatous polyps or early canceration using colonoscopy has been recognized. A clear colonoscopic vision brought by good intestinal preparation will become crucial. Several studies have completed using the low-residue diet (LRD) versus a clear liquid diet (CLD) the day before colonoscopy that presenting contradictory results. Therefore, a more comprehensive and updated meta-analysis is needed to summarize the findings on the effects of LRD and CLD on intestinal preparation and the quality of coloscopy. The comprehensive search was performed in PubMed/MEDLINE, Scopus, Cochrane databases (February 2020). LRD vs CLD before colonoscopy were included in this study. Mantel-Haenszel or DerSimonian and Laird models with the relative risk (RR) to evaluate differences in intestinal preparation, tolerance, readiness to repeat preparation, detected of a polyp, and overall adverse reactions. Total 16 studies (N = 3413) were eligible. Patients with LRD compared with CLD indicated significantly better of tolerability (RR 0.92;95% CI,0.85–0.99; P < .05) and willingness to repeat intestinal preparation (RR 0.86; 95% CI 0.79–0.93; P < .05), but no differences with adequate intestinal preparations, detected polyp or overall adverse reactions (all P > .05). Patients with LRD the day before colonoscopy show better tolerance and willingness to repeat intestinal preparation, and no difference with adequate intestinal preparations compared with CLD, but the recommended level of evidence is weak. However, in terms of the detection rate of intestinal adenomas, the LRD group is not weaker than the CLD group, for its evidence level is high, and can significantly reduce the hunger experience of patients.
Key Points: This article included a meta-analysis of 16 randomized control trials that included 3,413 participantsStudies found that both the low residue diet (LRD) group and the clear liquid diet (CLD) group were both well prepared for their colonoscopy after their bowel prep dayPolyp detection during the colonoscopy was the same in both groupsThere were no differences in any adverse reactions in either group89% of the LRD group reported that they were willing to go through another colonoscopy again in the future with their bowel prep regimen, while only 74% of the CLD group were willing to go through their bowel prep again for a future colonoscopyOnly 37% of the participants in the LRD group felt a hungry sensation on the day of the colonoscopy versus 53% of the participants in the CLD who felt hunger the morning of
Why I chose it: I chose this article because there were many more participants that were included in the study. Many different factors were included in the meta-analysis including adverse reactions to the type of prep that was used, willingness to repeat the bowel prep in the future, and if the participants were hungry on the day of the colonoscopy. Compared to a study of less than 200 participants from the first article, there were many similarities that I found, which I was very happy to see.  
Citation: Ahumada, C., Pereyra, L., Galvarini, M. et al. Efficacy and tolerability of a low-residue diet for bowel preparation: systematic review and meta-analysis. Surg Endosc 36, 3858–3875 (2022).
Type of article: Systematic review and meta-analysis
Abstract Background: Colorectal cancer (CRC) contributes significantly to cancer mortality worldwide. In an effort to reduce the risk of death, detection of polyps through colonoscopy is crucial. The success of the colonoscopy depends on the diet administered the day before the test. Our aim was to evaluate the efficacy, tolerability, and adverse effects of bowel preparation when using a low-residual diet (LRD) compared to a clear-liquid diet (CLD) the day before a scheduled colonoscopy. Methods: PubMed/Medline, Embase, the Cochrane Central Register of Controlled Trials (CENTRAL) and Scopus databases were searched. We included studies of patients undergoing a scheduled colonoscopy for CRC screening and surveillance or for diagnostic purposes that compared a LRD with a CLD the day before the colonoscopy. Efficacy, the primary outcome, was evaluated as the rate of adequate bowel preparation. Secondary outcomes were tolerability and adverse effects of bowel preparation. Results: Thirteen RCTs (N = 2587) were included. Patients receiving a LRD compared to a CLD showed no difference in adequate bowel preparations (RR 1.02; 95% CI 0.99–1.05; I2 = 60%). However, the LRD improved patient tolerability (RR 1.17; 95% CI 1.12–1.23; I2 = 66%) and had fewer adverse effects (RR 0.89; 95% CI 0.84–0.94; I2 = 73%) compared to the CLD. Groups using a LRD with 4L of polyethylene glycol in a single dose or a LRD with < 2000 kcal < 32 g of fiber/day had better tolerability. Conclusion: Based on these findings, our recommendation is strong in favor of a LRD for bowel preparation of patients undergoing a scheduled colonoscopy. This diet could also be useful as a preoperative colonic preparation, but this requires further research.
Key Points: This systematic review and meta-analysis looked at 2,587 patients who were assigned to a low residue diet (LRD) group or a clear liquid diet (CLD) groupAs mentioned before, there were no differences in the adequacy of the bowel preparation between both the LRD and the CLD groupsThere were no differences in the polyp detection in both groups as wellThe LRD group better tolerated the bowel prep and their diet a lot better than the CLD group didThe LRD had a lot less adverse reactions (like the rate of nausea, vomiting, and abdominal discomfort) versus the CLD group
Why I chose it: I chose this article because it reconfirmed what a lot of the other articles showed us. There was a large participant group that is always great to see. Unlike the other studies we have talked about (which only used polyethylene glycol as its bowel prep), this study looked at participants that used polyethylene glycol and other bowel preparations. This shows me regardless of what bowel preparation that was used, LRD was still better tolerated over a CLD.

What is the clinical “bottom line” derived from these articles in answer to your question?

Colorectal cancer is the second most prevalent cancer among men and the third most prevalent cancer among women in the United States. Colonoscopies are the gold-standard in screening and surveilling any possible problems that a patient might have. Bowel preparation is a very important factor for a very efficient and thorough colonoscopy, but patients often do not adhere to the steps of bowel prep because of demanding it may be. Clear liquid diets are the staple to effective bowel preparation, but low residue diets have been found to be more tolerable. Patients can eat a normalized breakfast, lunch, and dinner, and often do not find themselves too hungry the morning of their colonoscopies. If asked by a patient, I would recommend a low residue diet before bowel preparation for a colonoscopy.

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