Optimal Bowel Cleansing for Colonoscopy in the Elderly Patient

The Old: Is There Any Role for Screening Colonoscopy after the Age of 75? The Surgeon's Perspective

Guidelines recommend individualized decision making for screening colonoscopy for colorectal cancer (CRC) in patients after the age of 75 years due to low additional benefits. That should be taken with a grain of salt, as these recommendations are based on expert opinion and simulation models which do not consider (1) the differences in pathogenesis and cancer biology of CRC in elderly; (2) the risks of colonoscopy in this patient population; (3) and the impact of new surgical and nonsurgical therapies for CRC. In this review, our goal is to bring a surgeon's perspective to understand the role of screening colonoscopy in patients older than 75 years.

Colorectal Cancer Screening and Surveillance in the Geriatric Population

PURPOSE OF THE REVIEW

Our national guidelines regarding screening and surveillance for colorectal cancer recommend individualized discussions with patients 75-85 years of age. This review explores the complex decision-making that surrounds these discussions.

RECENT FINDINGS

Despite updated guidelines for colorectal cancer screening and surveillance, the guidance for patients 75 years of age or older remains unchanged. Studies exploring the risks to colonoscopy in this population, patient preferences, life expectancy calculators and additional studies in the subpopulation of inflammatory bowel disease patients provide points of consideration to aid in individualized discussions. The benefit-risk discussion for colorectal cancer screening in patients over 75 years old warrants further guidance to develop best practice. To craft more comprehensive recommendations, additional research with inclusion of such patients is needed.

Factors affecting the quality of bowel preparation for colonoscopy in hard-to-prepare patients: Evidence from the literature

Adequate bowel cleansing is critical for a high-quality colonoscopy because it affects diagnostic accuracy and adenoma detection. Nevertheless, almost a quarter of procedures are still carried out with suboptimal preparation, resulting in longer procedure times, higher risk of complications, and higher likelihood of missing lesions. Current guidelines recommend high-volume or low-volume polyethylene glycol (PEG)/non-PEG-based split-dose regimens. In patients who have had insufficient bowel cleansing, the colonoscopy should be repeated the same day or the next day with additional bowel cleansing as a salvage option. A strategy that includes a prolonged low-fiber diet, a split preparation regimen, and a colonoscopy within 5 h of the end of preparation may increase cleansing success rates in the elderly. Furthermore, even though no specific product is specifically recommended in the other cases for difficult-to-prepare patients, clinical evidence suggests that 1-L PEG plus ascorbic acid preparation are associated with higher cleansing success in hospitalized and inflammatory bowel disease patients. Patients with severe renal insufficiency (creatinine clearance < 30 mL/min) should be prepared with isotonic high volume PEG solutions. Few data on cirrhotic patients are currently available, and no trials have been conducted in this population. An accurate characterization of procedural and patient variables may lead to a more personalized approach to bowel preparation, especially in patients undergoing resection of left colon lesions, where intestinal preparation has a poor outcome. The purpose of this review was to summarize the evidence on the risk factors influencing the quality of bowel cleansing in difficult-to-prepare patients, as well as strategies to improve colonoscopy preparation in these patients.

Low-dose of magnesium sulfate solution was not inferior to standard regime of polyethylene glycol for bowel preparation in elderly patients: a randomized, controlled study

BACKGROUND

Large polyethylene glycol (PEG) is a standard regimen for bowel preparation. However, elderly patients suffered from adverse events. This study was to compare the efficacy and safety of oral magnesium sulfate solution (MSS) vs standard PEG in elderly patients undergoing colonoscopy.

METHODS

Elderly patients aged 60-90 years, from two endoscopic centers, were enrolled in China. Patients were randomized to take a low dose of MSS or a standard PEG regime in a split-dose regime. The primary endpoint was the proportion of patients with adequate bowel preparation, which was defined as the total Boston Bowel Preparation Scale (BBPS) ≥6 and each segmental BBPS was ≥2. Secondary outcomes included adenoma detection rate (ADR), safety, adverse events, cecal intubation rate, willingness to repeat BP, and so on.

RESULTS

1174 elderly patients were randomly allocated to the MSS group (n = 588) or the standard group (n = 586). Adequate BP was achieved in 94.0% of patients in the MSS group and 92.5% in the control (p = .287). ADR was also comparable between the two groups (43.0% and 39.9%, p = .282). Compared with the standard group, MSS group reported less abdominal discomfort (1.7% vs 6.0%), less nausea (13.6% vs 21.0%) and vomiting (1.2% vs 4.2%). The change in serum potassium levels after preparation in the standard group was significantly lower than that in the MSS group (-0.19 ± 0.08 vs -0.41 ± 0.11, p = .037).

CONCLUSIONS

Low dose of MSS was not inferior to the standard PEG regime in terms of bowel preparation quality for elderly patients. Low-dose MSS offered fewer adverse events and better tolerability. It is a preferable choice for the elderly to undergo bowel preparation for colonoscopy.

CLINICAL TRIAL REGISTRATION NUMBER

NCT04948567.

Endo-anesthesia: a primer

Gastrointestinal (GI) endoscopy has witnessed a Cambrian explosion of techniques, indications, and expanding target populations. GI endoscopy encompasses traditional domains that include preventive measures, palliation, as alternative therapies in patients with prohibitive risks of more invasive procedures, and indicated primary treatments. But, it has expanded to include therapeutic and diagnostic interventional endosonography, luminal endoscopic resection, third space endotherapy, endohepatology, and endobariatrics. The lines between surgery and endoscopy are blurred on many occasions within this paradigm. Moreover, patients with high degrees of co-morbidity and complex physiology require more nuanced peri-endoscopic management. The rising demand for endoscopy services has resulted in the development of endoscopy referral centers that offer these invasive procedures as directly booked referrals for regional and rural patients. This further necessitates specialized programs to ensure appropriate evaluation, risk stratification, and optimization for safe sedation and general anesthesia if needed. This landscape is conducive to the organic evolution of endo-anesthesia to meet the needs of these focused and evolving practices. In this primer, we delineate important aspects of endo-anesthesia care and provide relevant clinical and logistical considerations pertaining to the breadth of procedures.

Evaluation of the efficacy of 1 L polyethylene glycol plus ascorbic acid and an oral sodium sulfate solution: A multi-center, prospective randomized controlled trial

INTRODUCTION

Low-volume bowel preparation has been developed to increase patient compliance. We compared 1 L of polyethylene glycol/ascorbic acid (PEG/Asc) and oral sodium sulfate (OSS) with respect to bowel preparation efficacy, compliance, and safety.

METHODS

A multicenter, prospective, randomized, single-blinded, non-inferiority trial was conducted in 3 hospitals. Patients were randomized to receive a bowel-cleansing agent. Bowel-cleansing efficacy was evaluated using the Boston Bowel Preparation Scale (BBPS). Satisfaction, feeling, taste of the bowel cleanser, and adverse events after taking the bowel cleanser were investigated through a questionnaire. Additionally, blood samples were analyzed before and after bowel cleansing.

RESULTS

In total, 172 patients were analyzed (85 with 1 L PEG/Asc and 87 with OSS), and the mean BBPS scores were comparable between agents. The 1L PEG/Asc group tended to have a higher BBPS score in the right colon (2.22 vs 2.02; P = .08). The compliance of 1 L of PEG/Asc was comparable to that of OSS. Patients taking 1 L PEG/Asc reported greater thirst and dizziness (P = .04 and P = .047, respectively) than the OSS cohort. On the other hand, gastrointestinal symptoms such as vomiting and abdominal distension were more common in the OSS group, without statistical significance. In terms of laboratory adverse events, elevation of serum creatinine was found in both groups after taking the bowel cleansing agent (P < .001 for the 1L PEG/Asc group; P = .04 for the OSS group). However, most of the increased values were within the normal ranges.

DISCUSSION

The 1L PEG/Asc treatment was comparable to OSS in terms of bowel preparation efficacy, compliance, and safety.

Pre-colonoscopy special guidance and education on intestinal cleaning and examination in older adult patients with constipation

BACKGROUND

The prevalence of constipation in the Chinese population over 60 years of age is 11.5%, and this prevalence increases with age, which seriously affects the quality of life in older adults. Therefore, reducing the incidence of constipation in older adults is necessary to promote a healthy lifestyle as well as biochemical health.

AIM

To explore the value of preoperative guidance and education to improve the effects of bowel cleaning in older adult patients undergoing colonoscopy.

METHODS

In this study, 160 older adult patients with constipation requiring colonoscopy at Shandong Provincial Hospital between January 2019 and March 2021 were selected and randomly divided into a study group and a control group, with 80 patients in each group. The study group received medication guidance and targeted educational guidance before the operation, while the control group received only medication and dietary guidance. The baseline data, colonoscopy duration, bowel preparation compliance, Boston bowel preparation (BBPS) assessment score, intestinal bubble score, the incidence of adverse reactions during bowel preparation, and nursing appointment satisfaction were compared between the two groups.

RESULTS

The colonoscopy duration times and intestinal bubble scores of the study group were shorter than those of the control group, with statistically significant differences. The BBPS scores for the right, left, and interrupted colon in the study group were also higher than those in the control group, and the difference was statistically significant. Additionally, the study group had a higher rate of liquid diet one day before the examination, higher rate of correct bowel-clearing agent dilution method, higher rate of accurate time of ingesting the bowel-clearing agent, and a higher proportion of patients ingesting bowel-clearing agent at the specified time than the control group, with statistically significant differences. The incidence of nausea and vomiting during bowel clearance in the study group was significantly lower than that in the control group. The incidence of abdominal pain, abdominal distension, dizziness, and fatigue was compared between the two groups, but the difference was not statistically significant. The scores of service attitude, detailed notification of dietary precautions, clear and easy-to-understand health educational content, and receiving care and comfort in the study group were significantly higher than those in the control group.

CONCLUSION

Preoperative special guidance and education were shown to significantly improve bowel clearance and compliance and reduce the incidence of adverse reactions in older adult patients with constipation undergoing colonoscopy. These factors are beneficial for improving patient satisfaction with nursing services.

From advanced diagnosis to advanced resection in early neoplastic colorectal lesions: Never-ending and trending topics in the 2020s

Colonoscopy represents the most widespread and effective tool for the prevention and treatment of early stage preneoplastic and neoplastic lesions in the panorama of cancer screening. In the world there are different approaches to the topic of colorectal cancer prevention and screening: different starting ages (45-50 years); different initial screening tools such as fecal occult blood with immunohistochemical or immune-enzymatic tests; recto-sigmoidoscopy; and colonoscopy. The key aspects of this scenario are composed of a proper bowel preparation that ensures a valid diagnostic examination, experienced endoscopist in detection of preneoplastic and early neoplastic lesions and open-minded to upcoming artificial intelligence-aided examination, knowledge in the field of resection of these lesions (from cold-snaring, through endoscopic mucosal resection and endoscopic submucosal dissection, up to advanced tools), and management of complications.

Randomized trial of oral sulfate solution versus polyethylene glycol-ascorbic acid for bowel cleansing in elderly people

BACKGROUND AND AIM

The efficacy and safety of the recently introduced low-volume purgatives in elderly people are not well known. Therefore, in this trial, we aimed to evaluate and compare the efficacy of two low-volume agents, oral sulfate solution (OSS) and 2-L polyethylene glycol with ascorbic acid (PEG-Asc), in elderly people.

METHODS

A prospective, randomized, single-blinded, multicenter, non-inferiority trial was performed at three university-affiliated hospitals in South Korea. Outpatients aged 65-80 years, who underwent elective colonoscopy, were enrolled. The primary outcome was the rate of adequate bowel preparation assessed using the Boston Bowel Preparation Scale.

RESULTS

A total of 199 subjects were randomized into the OSS (n = 99) or the 2-L PEG-Asc (n = 100) group. Of them, 189 subjects were included in the analysis of the primary outcome (OSS group 95 vs PEG-Asc group 94). The proportion of adequate bowel preparation was 89.5% (85/95) in the OSS group and 93.6% (88/94) in the 2-L PEG-Asc group. OSS was not inferior to 2-L PEG-Asc according to the prespecified non-inferiority margin of -15% (95% confidence interval for the difference, -12.1 to 3.8). Vomiting (11.6% vs 2.1%) and thirst (24.2% vs 11.7%) were more common in the OSS group than in the 2-L PEG-Asc group.

CONCLUSIONS

OSS is an effective low-volume purgative that is non-inferior to 2-L PEG-Asc in elderly people. Both the low-volume agents were identified to be well tolerated and safe in the healthy elderly population.

Validation and Application of Predictive Models for Inadequate Bowel Preparation in Colonoscopies in a Tertiary Hospital Population

Background: Bowel preparation is a major quality criterion for colonoscopies. Models developed to identify patients with inadequate preparation have not been validated in external cohorts. We aim to validate these models and determine their applicability. Methods: Colonoscopies between April and November 2019 were retrospectively included. Boston Bowel Preparation Scale ≥2 per segment was considered adequate. Insufficient data, incomplete colonoscopies, and total colectomies were excluded. Two models were tested: model 1 (tricyclic antidepressants, opioids, diabetes, constipation, abdominal surgery, previous inadequate preparation, inpatient status, and American Society of Anesthesiology [ASA] score ≥3); model 2 (co-morbidities, tricyclic antidepressants, constipation, and abdominal surgery). Results: We included 514 patients (63% males; age 61.7 ± 15.6 years), 441 with adequate preparation. The main indications were inflammatory bowel disease (26.1%) and endoscopic treatment (24.9%). Previous surgery (36.2%) and ASA score ≥3 (23.7%) were the most common comorbidities. An ASA score ≥3 was the only identified predictor for inadequate preparation in this study (p < 0.001, OR 3.28). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of model 1 were 60.3, 64.2, 21.8, and 90.7%, respectively. Model 2 had a sensitivity, specificity, PPV, and NPV of 57.5, 67.4, 22.6, and 90.5%, respectively. The AUC for the ROC curves was 0.62 for model 1, 0.62 for model 2, and 0.65 for the ASA score. Conclusions: Although both models accurately predict adequate bowel preparation, they are still unreliable in predicting inadequate preparation and, as such, new models, or further optimization of current ones, are needed. Utilizing the ASA score might be an appropriate approximation of the risk for inadequate bowel preparation in tertiary hospital populations.

Colonoscopy-related colonic ischemia

Colonoscopy is a risk factor for colon ischemia. The colon is susceptible to ischemia due to its minor blood flow compared to other abdominal organs; the etiology of colon ischemia after colonoscopy is multifactorial. The causative mechanisms include splanchnic circulation impairment, bowel preparation, drugs used for sedation, bowel wall ischemia due to insufflation/barotrauma, and introduction of the endoscope. Gastroenterologists must be aware of this condition and its risk factors for risk minimization, early diagnosis, and proper treatment.

Safe and appropriate use of laxatives for colonoscopy

Background: Appropriate bowel preparation is essential for effective colonoscopy. Inadequate use of bowel preparation solutions reduces patient compliance, makes the detection of lesions such as adenoma difficult, and increases the risk of complication such as perforation. Current Concepts: A 4-L polyethylene glycol (PEG) solution can be safely used for bowel preparation, even in most individuals with underlying diseases. However, it requires a high preparation-volume intake and has poor patient compliance due to its unpleasant taste. Therefore, a 2- or 1- L sulfate-free, PEG-based laxative was developed to, reduce the amount of PEG and improve the taste. Furthermore, simethicon-containing laxative formulation was developed to eliminate gas bubbles. In addition, oral bowel preparation solutions with enema agents and prokinetics were used to improve bowel preparation, but no improvement was observed. Various alternative laxatives are available; however, PEG-based bowel preparation solutions are still recommended in most cases due to their stability. Discussion and Conclusion: Although a 4-L PEG solutions recommended for bowel preparation in most cases, several laxatives have been introduced to overcome its disadvantages. The laxative agent must be selected according to each patient’s specific characteristics. Moreover, the method of taking bowel preparation solutions and additional bowel preparation medications must be carefully chosen. In addition, patient education via various methods, such as using a smartphone, when taking a bowel preparation agent may help improve bowel preparation quality.

Primary care clinicians' perceptions of colorectal cancer screening tests for older adults

Colonoscopy is an effective screening test for colorectal cancer but is associated with significant risks and burdens, especially in older adults. Stool tests, which are more convenient, more accessible, and less invasive, can be important tools to improve screening. How clinicians make decisions about colonoscopy versus stool tests in older patients is not well-understood. We conducted semi-structured interviews with primary care clinicians throughout Maryland in 2018-2019 to examine how clinicians considered the use of stool tests for colorectal cancer screening in their older patients. Thirty clinicians from 21 clinics participated. The mean clinician age was 48.2 years. The majority were physicians (24/30) and women (16/30). Four major themes were identified using qualitative content analysis: (1) Stool test equivalency - although many clinicians still considered colonoscopy as the test of choice, some clinicians considered stool tests equivalent options for screening. (2) Reasons for recommending stool tests - clinicians reported preferentially using stool tests in sicker/older patients or patients who declined colonoscopy. (3) Stool test overuse - some clinicians reported recommending stool tests for patients for whom guidelines do not recommend any screening. (4) Barriers to use - perceived barriers to using stool tests included lack of familiarity, un-returned stool test kits, concern for accuracy, and concern about cost. In summary, clinicians reported preferentially using stool tests in sicker and older patients and mentioned examples of potential overuse. Additional studies are needed on how to better individualize the use of different colorectal screening tests in older patients.

Factors affecting bowel preparation adequacy and procedural time

Background and Aim

Poor bowel preparation results in difficult colonoscopies, missed lesions, and repeat procedures. Identifying patient risk factors for poor bowel preparation, such as prolonged runway time and prolonged cecal intubation, will aid in interventions prior to a procedure.

Methods

This was a retrospective, single‐center analysis of 3 295 colonoscopies performed between May 2012 and November 2014. Indications for colonoscopy included gastrointestinal bleed and anemia, change in bowel habits, for screening, and others (including planning re‐anastomoses, abdominal distension, family history and angioectasias). Data were collected from medical charts and endoscopy reports. Comparisons between patient factors and runway time were made with adequacy of bowel preparation as the primary outcomes.

Results

Male and diabetic patients had statistically higher rates of inadequate bowel preparation and prolonged cecal intubation times. A previous history of abdominal surgery also demonstrated prolonged cecal intubation. A runway time of ≤7.63 h was associated with higher rates of adequate bowel preparation by multivariate analysis. The optimal time frame is 3–6 h for the highest success rates.

Conclusion

Patient risk factors for inadequate bowel preparation or prolonged cecal intubation should signal clinicians to intervene prior to colonoscopy. A runway time between 3 and 6 h is optimal for adequate bowel preparation. This may involve further patient education, along with work flow optimization, to facilitate ideal runway times. Future studies should explore how to avoid repeat endoscopies using protocols enforcing this timeframe.

Efficacy, safety, and tolerability of a ready-to-drink bowel preparation: subanalysis by age from a phase III, assessor-blinded study

BACKGROUND

The incidence and mortality of colorectal cancer (CRC) increase with age and, therefore, it is recommended that adults undergo regular CRC screening, ideally by colonoscopy, with some new guidelines recommending screening begin at 45 years. Effective bowel preparation is a critical step to a successful colonoscopy. Of concern is that older adults may have poorer quality of bowel preparation or reduced tolerability for the bowel preparation. Here, we performed a post hoc secondary analysis for the effect of age on the efficacy, tolerability, and safety of ready-to-drink sodium picosulfate, magnesium oxide, and citric acid (SPMC oral solution) bowel preparation.

METHODS

A phase III, randomized, assessor-blinded, multicenter, non-inferiority study was conducted comparing split-dose, low-volume SPMC oral solution with split-dose, low-volume sodium picosulfate, magnesium oxide, and citric acid powder for oral solution. A post hoc secondary analysis was performed to assess efficacy, safety, and tolerability of SPMC oral solution by age group (<50 years, 50-64 years, ⩾65 years). The prespecified primary efficacy endpoint ('responders') was the proportion of participants with 'excellent' or 'good' ratings on a modified Aronchick Scale (AS). Secondary efficacy outcomes were the quality of cleansing of the right colon as assessed by the Boston Bowel Preparation Scale (BBPS); as well as selected findings from the Mayo Clinic Bowel Prep Tolerability Questionnaire. Safety assessments included adverse events (AEs) and laboratory evaluations.

RESULTS

Within age groups, at least 83.9% of participants were responders by the AS, and at least 91.1% of participants were responders by the BBPS in the right colon. On both scales, responder rates were highest in the youngest age group and decreased with increasing age. Greater than 88% of participants in any age group found the preparation 'easy' or 'acceptable' to ingest, with rates of 'easy' being highest in the oldest age group. No new safety signals were seen in any age group. The most commonly reported drug-related, treatment-emergent AEs were, by ascending age group, nausea (7.0%, 3.2%, 0.8%), headache (4.2%, 2.8%, 1.6%) and vomiting (2.8%, 1.2%, 0.8%).

CONCLUSION

Ready-to-drink SPMC oral solution showed good efficacy of overall colon cleansing and tolerability in adults across different age groups, including those ⩾65 years.ClinicalTrials.gov identifier: NCT03017235.

Same-Day Single Dose of 2 Liter Polyethylene Glycol is Not Inferior to The Standard Bowel Preparation Regimen in Low-Risk Patients: A Randomized, Controlled Trial

OBJECTIVES

Split dose of 4 l polyethylene glycol (PEG) is currently the standard regimen for bowel preparation (BP). However, it may be unnecessary for patients without high risks (e.g., old age, constipation, and diabetes, and so on) for inadequate BP. The study aimed to compare the efficacy of bowel cleansing between low-risk patients receiving same-day, single dose of low-volume (SSL) PEG vs. standard regimen.

METHODS

This prospective, randomized, observer-blinded, non-inferiority study enrolled low-risk patients in three centers. Patients undergoing colonoscopy were randomized (1:1) to the SSL or standard group. The primary outcome was adequate BP, defined by Boston Bowel Preparation Score (BBPS) ≥6 and each segmental score ≥2. Secondary outcomes included adverse events, cecal intubation rate, and patient willingness to repeat BP, and so on.

RESULTS

Among 2,532 patients eligible for the study, 940 (37.1%) were at low risk and 792 (31.3%) at high risk for inadequate BP. The low-risk patients were randomly allocated to the SSL (n=470) or standard group (n=470). The baseline characteristics of the two groups were similar. Intention-to-treat analysis showed that adequate BP was achieved in 88.1% in the SSL group and 87.0% in the standard group (relative risk (RR) 1.10, 95% confidence interval (CI): 0.75-1.63, P=0.621). The overall BBPS was 7.3±1.2 and 7.3±1.3, respectively (P=0.948). No significant differences were found between the two groups with regards to the right, transverse, and left-segmental colon BBPS (all P>0.05). However, in terms of adverse events, patients in the SSL group reported less nausea (19.6% vs. 29.9%), vomiting (5.3% vs. 11.4%), and abdominal discomfort (2.2% vs. 6.0%) compared with those in the standard group. More patients in the SSL group were willing to repeat BP (94.0% vs. 89.5%, P=0.015).

CONCLUSIONS

For low-risk patients, the SSL regimen was not inferior to the split dose of 4 l PEG for adequacy of BP. Single dose of low-volume regimen had significantly fewer adverse events. This simplified regimen may be preferable in the "easy-to prepare" population.

The incidence of and risk factors for inadequate bowel preparation in elderly patients: A prospective observational study

BACKGROUND/AIM

: We conducted a prospective observational study to identify the incidence of and risk factors for inadequate bowel preparation in elderly Chinese patients.

PATIENTS AND METHODS

We enrolled 240 outpatients over 60 years of age scheduled for elective colonoscopy at our university hospital between November 2016 and April 2017. We recorded patient demographics, bowel preparation data, and clinical characteristics. Factors associated with inadequate bowel preparation were identified by multivariate logistical regression analysis.

RESULTS

The rate of inadequate bowel preparation was 34.6%. Factors associated with inadequate bowel preparation were a history of abdominal surgery (OR, 2.617; CI, 1.324-5.174; P = 0.006), chronic constipation (OR, 3.307; CI, 1.551-7.054; P = 0.002), non-compliance with dietary instructions (OR, 2.239; CI, 1.122-4.471; P = 0.022), non-compliance with polyethylene glycol (PEG) dosage (OR, 4.576; CI, 1.855-11.287; P = 0.001), walking <30 minutes during preparation (OR, 2.474; CI, 1.261-4.855; P = 0.008), interval between PEG ingestion and the onset of bowel activity (OR, 1.025; CI, 1.010-1.040; P = 0.001), and a last stool that was not clear and watery (OR, 4.191; CI, 1.529-11.485; P = 0.005).

CONCLUSION

The incidence of adequate bowel preparation in elderly patients is not optimal. Walking <30 minutes during the PEG ingestion period may be a surrogate for bowel preparation failure. Future studies should identify elderly patients at risk for poor bowel preparation and develop interventions to improve outcomes in this population.