Ascorbic acid and low-volume polyethylene glycol for bowel preparation prior to colonoscopy: A meta-analysis

Can adjuncts to bowel preparation for colonoscopy improve patient experience and result in superior bowel cleanliness? A systematic review and meta-analysis

BACKGROUND

Bowel preparation for colonoscopy is often poorly tolerated due to poor palatability and adverse effects. This can negatively impact on the patient experience and on the quality of bowel preparation. This systematic review and meta-analysis was carried out to assess whether adjuncts to bowel preparation affected palatability, tolerability and quality of bowel preparation (bowel cleanliness).

METHODS

A systematic search strategy was conducted on PubMed, MEDLINE, EMBASE and the Cochrane Database of Systematic Reviews to identify studies evaluating adjunct use for colonoscopic bowel preparation. Studies comparing different regimens and volumes were excluded. Specific outcomes studied included palatability (taste), willingness to repeat bowel preparation, gastrointestinal adverse events and the quality of bowel preparation. Data across studies were pooled using a random-effects model and heterogeneity assessed using I2-statistics.

RESULTS

Of 467 studies screened, six were included for analysis (all single-blind randomised trials; n = 1187 patients). Adjuncts comprised citrus reticulata peel, orange juice, menthol candy drops, simethicone, Coke Zero and sugar-free chewing gum. Overall, adjunct use was associated with improved palatability (mean difference 0.62, 95% confidence interval 0.29-0.96, p < 0.001) on a scale of 0-5, acceptability of taste (odds ratio 2.75, 95% confidence interval: 1.52-4.95, p < 0.001) and willingness to repeat bowel preparation (odds ratio 2.92, 95% confidence interval: 1.97-4.35, p < 0.001). Patients in the adjunct group reported lower rates of bloating (odds ratio 0.48, 95% confidence interval: 0.29-0.77, p = 0.003) and vomiting (odds ratio 0.47, 95% confidence interval 0.27-0.81, p = 0.007), but no difference in nausea (p = 0.10) or abdominal pain (p = 0.62). Adjunct use resulted in superior bowel cleanliness (odds ratio 2.52, 95% confidence interval: 1.31-4.85, p = 0.006). Heterogeneity varied across outcomes, ranging from 0% (vomiting) to 81% (palatability), without evidence of publication bias. The overall quality of evidence was rated moderate.

CONCLUSION

In this meta-analysis, the use of adjuncts was associated with better palatability, less vomiting and bloating, willingness to repeat bowel preparation and superior quality of bowel preparation. The addition of adjuncts to bowel preparation may improve outcomes of colonoscopy and the overall patient experience.

Strategies to Improve Inadequate Bowel Preparation for Colonoscopy

Bowel cleansing is one of the most important parameters included in the evaluation of colonoscopy quality. The available evidence suggests that inadequate bowel preparation reduces the diagnostic yield of colorectal neoplasia and increases post-colonoscopy colorectal cancer risk. Nowadays, up to 30% of patients referred for colonoscopy have a poor bowel cleansing. Recently, several studies have analyzed the risk factors for inadequate bowel cleansing as well as the strategies to optimize bowel preparation. In this review, we have focused on summarizing the available evidence in this field.

Comparative Efficacy of 2 L Polyethylene Glycol Alone or With Ascorbic Acid vs. 4 L Polyethylene Glycol for Colonoscopy: A Systematic Review and Network Meta-Analysis of 12 Randomized Controlled Trials

Background: Colonoscopy remains an optimal approach for early detection and treatment of gastrointestinal lesions, however adequate bowel preparation is the critical contributor to effective and safe colonoscopy. Polyethylene glycol (PEG)-based bowel cleansing regime has been the first recommendation before colonoscopy, however it remains unknown which regime is the optimal option. Aim: The aim of our study is to determine the comparative efficacy of 2 L PEG alone or plus ascorbic acid (Asc) vs. 4 L PEG alone for bowel cleansing prior to colonoscopy. Methods: We assigned two independent investigators to search and screen potential records, extract essential information, and appraise the risk of bias of individual study accordingly. Then, we adopted RevMan 5.3, Stata 14.0, and WinBUGS 1.4 software to perform all statistical analyses. We also calculated the surface under the cumulative ranking curve (SCURA) in order to rank all regimes. Results: Twelve studies involving 4,106 patients were analyzed finally. Pooled results indicated an improved bowel preparation efficacy in 2 L PEG plus ascorbic acid with split-dose regime rather than in 2 L PEG plus ascorbic acid (OR, 0.25; 95% CI, 0.18-0.36), 4 L PEG with split dose (OR, 3.18; 95% CI, 2.17-4.66), and 4 L PEG (OR, 4.53; 95% CI, 3.07-6.67) regimes, which was confirmed by network meta-analyses; a better compliance in 2 L PEG plus Asc with split dose (OR, 3.08; 95% CI, 1.51-6.30) and 4 L PEG with split dose (OR, 0.43; 95% CI, 0.22-0.82) regime rather than in 4 L PEG regime, but network meta-analyses generated inconsistency results; a higher preference in 2 L PEG plus Asc with split dose regime rather than in 4 L PEG split dose (OR, 2.24; 95% CI, 1.02-4.90), which were not supported by network meta-analyses; no statistically significant difference when all regimes compared with each other in terms of adverse events. Conclusions: As for bowel preparation before colonoscopy, 2 L PEG ascorbic acid with split dose should be optimally prescribed. Further studies investigating the comparative efficacy of 2 L PEG related to 4 L PEG, 4 L PEG with split dose, and 2 L PEG plus ascorbic acid with split dose, respectively are needed.

Miralax with gatorade for bowel preparation: a meta-analysis of randomized controlled trials

OBJECTIVES

Polyethylene glycol (PEG) is a very popular bowel preparation for colonoscopy. However, its large volume may reduce patient compliance, resulting in suboptimal preparation. Recently, a combination of Miralax and Gatorade has been studied in various randomized controlled trials (RCTs) as a lower volume and more palatable bowel preparation. However, results have varied. Therefore, we conducted a meta-analysis assessing the use of Miralax-Gatorade (M-G) vs. PEG for bowel preparation before colonoscopy.

METHODS

Multiple databases were searched (January 2014). RCTs on adults comparing M-G (238-255 g in 1.9 l that is 64 fl oz) vs. PEG (3.8-4 l) for bowel preparation before colonoscopy were included. The effects were analyzed by calculating pooled estimates of quality of bowel preparation (satisfactory, unsatisfactory, excellent), patient tolerance (nausea, cramping, bloating), and polyp detection by using odds ratio (OR) with fixed- and random-effects models.

RESULTS

Five studies met inclusion criteria (N=1,418), with mean age ranging from 53.8 to 61.3 years. M-G demonstrated statistically significantly fewer satisfactory bowel preparations as compared with PEG (OR 0.65; 95% confidence interval (CI): 0.43-0.98, P=0.04) but more willingness to repeat preparation (OR 7.32; 95% CI: 4.88-10.98, P<0.01). Furthermore, no statistically significant differences in polyp detection (P=0.65) or side effects were apparent between the two preparations for nausea (P=0.71), cramping (P=0.84), or bloating (P=0.50). Subgroup analysis revealed similar results for split-dose M-G vs. split-dose PEG.

CONCLUSIONS

M-G for bowel preparation before colonoscopy was inferior to PEG in bowel preparation quality while demonstrating no significant improvements in adverse effects or polyp detection. Therefore, PEG appears superior to M-G for bowel preparation before colonoscopy.

A meta-analysis of randomized controlled trials of low-volume polyethylene glycol plus ascorbic acid versus standard-volume polyethylene glycol solution as bowel preparations for colonoscopy

BACKGROUND

Standard-volume polyethylene glycol (PEG) gut lavage solutions are safe and effective, but they require the consumption of large volumes of fluid. A new lower-volume solution of PEG plus ascorbic acid has been used recently as a preparation for colonoscopy.

AIM

A meta-analysis was performed to compare the performance of low-volume PEG plus ascorbic acid with standard-volume PEG as bowel preparation for colonoscopy.

STUDY

Electronic and manual searches were performed to identify randomized controlled trials (RCTs) that compared the performance of low-volume PEG plus ascorbic acid with standard-volume PEG as bowel preparation for colonoscopy. After a methodological quality assessment and data extraction, the pooled estimates of bowel preparation efficacy during bowel cleansing, compliance with preparation, willingness to repeat the same preparation, and the side effects were calculated. We calculated pooled estimates of odds ratios (OR) by fixed- and/or random-effects models. We also assessed heterogeneity among studies and the publication bias.

RESULTS

Eleven RCTs were identified for analysis. The pooled OR for preparation efficacy during bowel cleansing and for compliance with preparation for low-volume PEG plus ascorbic acid were 1.08 (95% CI = 0.98-1.28, P = 0.34) and 2.23 (95% CI = 1.67-2.98, P<0.00001), respectively, compared with those for standard-volume PEG. The side effects of vomiting and nausea for low-volume PEG plus ascorbic acid were reduced relative to standard-volume PEG. There was no significant publication bias, according to a funnel plot.

CONCLUSIONS

Low-volume PEG plus ascorbic acid gut lavage achieved non-inferior efficacy for bowel cleansing, is more acceptable to patients, and has fewer side effects than standard-volume PEG as a bowel preparation method for colonoscopy.