Low-Volume Split-Dose PEG as Effective as High-Volume Split-Dose PEG

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Low-volume, split-dose regimens of polyethylene glycol are better tolerated and appear to be as effective as high-volume, split-dose regimens for bowel preparation before colonoscopy.

Low-volume, split-dose regimens of polyethylene glycol (PEG) are better tolerated and appear to be as effective as high-volume, split-dose regimens for bowel preparation before colonoscopy, according to a study published in Clinical Gastroenterology and Hepatology.

In this systematic review and meta-analysis, researchers conducted a comprehensive literature search utilizing PubMed/MEDLINE, EMBASE, and Scopus through January 31, 2019, to identify randomized controlled trials comparing low- and high-volume bowel preparation before colonoscopy. Patients in the intention-to-treat analysis (N=7528) were divided into a low-volume split-dose group (n=3749) and a high-volume split-dose group (n=3779). The primary outcome was bowel preparation efficacy; secondary outcomes included patient adherence to the regimen, willingness to repeat the same bowel solution, palatability of the regimen, and side effects.

Low-volume split-dose bowel regimens had an equivalent proportion of patients with an adequate bowel preparation compared with split-dose high-volume PEG (86.1%; 95% CI, 82.6-90% vs 87.4%; 95% CI, 84.1-90.7%; risk ratio [RR], 1.00; 95% CI, 0.98-1.02; P =.2).

In the 10 studies reporting data on the right colon (n=5288), there was no difference in efficacy between low-PEG and non-PEG volume and high-volume PEG regimens (91.2%; 95% CI, 89.1-93.3% vs 89.6%; 95% CI, 87.3-92%; RR, 1.01; 95% CI, 0.99-1.03; P =.22).

There was no difference in efficacy of right colon cleansing between low-volume non-PEG and high-volume PEG regimens [3 studies, n=483 patients; 92.2%; 95% CI, 88.8-95.6% vs 91.4%; 95% CI, 87.9-94.9%; RR, 1.01; 95% CI, 0.96-1.06; P =.99). Patients receiving low-volume PEG and non-PEG regimens were more likely to complete the preparation than those receiving high-volume volume preparation (92.8%; 95% CI, 89.6-96.1% vs 86.8%; 95% CI, 82.1-91.4%; RR, 1.06; 95% CI, 1.02-1.10; P <.01).

Limitations of this study included selection bias intrinsic in high-quality randomized trials. Caution should be exercised when prescribing these agents to frail or severely ill patients. The problem with all of the meta-analyses on bowel preparation, including this one, is that the primary outcome is not homogeneously reported across the included studies because different scales were used. Researchers corroborated these findings through a subgroup analysis that pooled the data from studies that used comparable definitions for bowel preparation and cleansing.

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“Our analysis shows that the low-volume PEG and non-PEG regimens are comparative to high-volume PEG regimen which is different when compared to the previous meta-analysis showing superiority in efficacy of a high-volume PEG over a low-volume PEG regimen used in a split dose,” the researchers concluded. “When coupling the equivalent efficacy with a better experience, there is compelling evidence to recommend a low-volume split regimen as alternative to the high-volume regimen, unless additional factors, such as cost or patient preferences, supports a different choice.”

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.


Spadaccini M, Frazzoni L, Vanella G, et al. Efficacy and tolerability of high- vs low-volume split-dose bowel cleansing regimens for colonoscopy: a systematic review and meta-analysis [published online November 1, 2019]. Clin Gastroenterol Hepatol. doi: 10.1016/j.cgh.2019.10.044