Financial conflicts of interest and reporting bias regarding the association between sugar-sweetened beverages and weight gain: a systematic review of systematic reviews

摘要

Background: Industry sponsors’ financial interests might bias the conclusions of scientific research. We examined whetherfinancial industry funding or the disclosure of potential conflicts of interest influenced the results of published systematicreviews (SRs) conducted in the field of sugar-sweetened beverages (SSBs) and weight gain or obesity.Methods and Findings: We conducted a search of the PubMed, Cochrane Library, and Scopus databases to identifypublished SRs from the inception of the databases to August 31, 2013, on the association between SSB consumption andweight gain or obesity. SR conclusions were independently classified by two researchers into two groups: those that founda positive association and those that did not. These two reviewers were blinded with respect to the stated source of fundingand the disclosure of conflicts of interest. We identified 17 SRs (with 18 conclusions). In six of the SRs a financial conflict ofinterest with some food industry was disclosed. Among those reviews without any reported conflict of interest, 83.3% of theconclusions (10/12) were that SSB consumption could be a potential risk factor for weight gain. In contrast, the samepercentage of conclusions, 83.3% (5/6), of those SRs disclosing some financial conflict of interest with the food industrywere that the scientific evidence was insufficient to support a positive association between SSB consumption and weightgain or obesity. Those reviews with conflicts of interest were five times more likely to present a conclusion of no positiveassociation than those without them (relative risk: 5.0, 95% CI: 1.3–19.3). An important limitation of this study is theimpossibility of ruling out the existence of publication bias among those studies not declaring any conflict of interest.However, the best large randomized trials also support a direct association between SSB consumption and weight gain orobesity.Conclusions: Financial conflicts of interest may bias conclusions from SRs on SSB consumption and weight gain or obesity.