4-Liter Split-Dose Polyethylene Glycol Is Superior to Other Bowel Preparations, Based on Systematic Review and Meta-analysis

BACKGROUND & AIMS: Adequate bowel cleansing is an important determinant of the efficacy of screening colonoscopy. Polyethylene glycol (PEG)-based solutions are used commonly in bowel preparation, but their poor palatability and large volumes (4 L) influence compliance. Adjunct therapies, such as bisacodyl, split-dose regimens, and lower-volume regimens have been tested. We performed a meta-analysis to determine whether a 4-L split dose of PEG is better than others for bowel cleansing before colonoscopy. METHODS: We searched MEDLINE, the Cochrane Central Register of Controlled Trials and Database, recent abstracts from major conference proceedings, references from selected reviews and randomized trials (http://clinicaltrials.gov), and Google Scholar, through September 2011, for high-quality, randomized trials that compared 4-L split-dose PEG without adjunct therapy with other bowel preparation methods. Nine of 2477 trials considered were used in the analysis. We calculated pooled estimates of bowel preparation quality (primary outcome: excellent or good), preparation compliance, favorable overall experiences, willingness to repeat same preparation, and side effects. We calculated pooled estimates of odds ratios by fixed-and random-effects models. We also assessed heterogeneity among studies and publication bias. RESULTS: The overall pooled odds ratio for excellent or good bowel preparation quality for 4-L split-dose PEG was 3.46, compared with other methods (95% confidence interval, 2.45-4.89; P < .01). Although there was significant heterogeneity in results among studies, 7 of 9 reported a significant benefit from the 4-L split-dose PEG preparation. There were no significant differences between PEG and others in preparation compliance, favorable overall experience, willingness to repeat the same preparation, abdominal cramping, nausea, or sleep disturbance. There was no significant publication bias based on funnel plot. CONCLUSIONS: A meta-analysis showed that 4-L split-dose PEG is better than other bowel preparation methods for colonoscopy. Significant heterogeneity among studies might result from differences in patient demographics and protocols. A 4-L split dose of PEG should be considered the standard with which new bowel preparation methods are compared.