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.

Gold standard medical therapy for glaucoma: defining the criteria identifying measures for an evidence-based analysis.

BACKGROUND: Over the past decade, several new medical therapies have become available for the treatment of primary open-angle glaucoma (POAG). A systematic evidence-based approach for identifying an optimal therapeutic agent is lacking. OBJECTIVES: The aims of this review were to critically evaluate published treatment recommendations for POAG and, based on a systematic review of the literature, to develop criteria that would define a "gold standard" medical therapy that reflects new treatment advances and established therapeutic goals. METHODS: A MEDLINE search spanning the years 1966 to 2002 and using the search terms gold standard, drug of choice, agent of choice, benchmark, ophthalmology, eye, and glaucoma was conducted and the results reviewed by a panel of 15 experts in the field of glaucoma. Published treatment recommendations for POAG were discussed. Criteria, anchored to medical evidence, for distinguishing a standard of medical therapy for POAG were defined. RESULTS: The terms connoting a gold standard therapy were found in only 258 of approximately 368,000 ophthalmology-related citations and 53 of almost 23,000 glaucoma citations, validating the need to define therapeutic standards. The lack of recommendations for the use of new classes of ocular hypotensive agents was acknowledged. Criteria identified to evaluate intraocular pressure (IOP)-lowering agents as gold standards included the following: efficacy in reducing IOP consistently over a 24-hour period to a level that will preserve the visual field and protect the optic nerve without inducing tachyphylaxis and tolerance, paucity of local and systemic adverse effects, promotion of patient compliance, and applicability in diverse patient populations. CONCLUSIONS: These criteria should be employed as measures for evidence-based analyses to evaluate available and future IOP-lowering medical therapies for POAG. The conceptual framework presented may be applicable to other therapeutic areas.