Quality of reviews on sugar-sweetened beverages and health outcomes: a systematic review

Abstract

Background: Medical and public health decisions are informed by reviews, which makes the quality of reviews an important scientific concern.

Objective: We systematically assessed the quality of published reviews on sugar-sweetened beverages (SSBs) and health, which is a controversial topic that is important to public health.

Design: We performed a search of PubMed and Cochrane databases and a hand search of reference lists. Studies that were selected were published reviews and meta-analyses (June 2001 to June 2011) of epidemiologic studies of the relation between SSBs and obesity, type 2 diabetes, metabolic syndrome, and coronary heart disease. A standardized data-abstraction form was used. Review quality was assessed by using the validated instrument AMSTAR (assessment of multiple systematic reviews), which is a one-page tool with 11 questions.

Results: Seventeen reviews met our inclusion and exclusion criteria: obesity or weight (16 reviews), diabetes (3 reviews), metabolic syndrome (3 reviews), and coronary heart disease (2 reviews). Authors frequently used a strictly narrative review (7 of 17 reviews). Only 6 of 17 reviews reported quantitative data in a table format. Overall, reviews of SSBs and health outcomes received moderately low-quality scores by the AMSTAR [mean: 4.4 points; median: 4 points; range: 1-8.5 points (out of a possible score of 11 points)]. AMSTAR scores were not related to the conclusions of authors (8 reviews reported an association with a mean AMSTAR score of 4.1 points; 9 reviews with equivocal conclusions scored 4.7 points; P value = 0.84). Less than one-third of published reviews reported a comprehensive literature search, listed included and excluded studies, or used duplicate study selection and data abstraction.

Conclusion: The comprehensive reporting of epidemiologic evidence and use of systematic methodologies to interpret evidence were underused in published reviews on SSBs and health.

FIGURE 1.

Results of a search for published reviews and meta-analyses that focused predominately on sugar-sweetened beverages and health outcomes. ^aReasons for exclusion on review of the title or published abstract (PubMed, www.ncbi.nlm.nih.gov/pubmed); ^bpublications that were not related to this review (examples included, but were not limited to, studies of dietary patterns and coffee, tea, or alcohol consumption; ^ctitle suggested possible inclusion, but abstract review showed that the publication was not focused on analytic epidemiologic studies (eg, mechanistic studies, descriptive epidemiology, or commentary); ^dpublications that included some discussion of epidemiologic studies of sugar-sweetened beverages and the outcome of interest but as one of many focuses of the article; ^earticles were included if the stated goal or approach implied an attempt to summarize all available literature (one article was excluded because the stated goal was to review “some of the latest research”). CHD, coronary heart disease; MetSyn, metabolic syndrome; ref., reference; T2DM, type 2 diabetes.