Relationship between Research Outcomes and Risk of Bias, Study Sponsorship, and Author Financial Conflicts of Interest in Reviews of the Effects of Artificially Sweetened Beverages on Weight Outcomes: A Systematic Review of Reviews.
BACKGROUND
Artificially sweetened beverage consumption has steadily increased in the last 40 years. Several reviews examining the effects of artificially sweetened beverages on weight outcomes have discrepancies in their results and conclusions.


OBJECTIVE
To determine whether risk of bias, results, and conclusions of reviews of effects of artificially sweetened beverage consumption on weight outcomes differ depending on review sponsorship and authors' financial conflicts of interest.


METHODS
We performed a systematic review of reviews of the effects of artificially sweetened beverages on weight. Two assessors independently screened articles for inclusion, extracted data, and assessed risks of bias. We compared risk of bias, results and conclusions of reviews by different industry sponsors, authors' financial conflict of interest and journal sponsor. We also report the concordance between review results and conclusions.


RESULTS
Artificial sweetener industry sponsored reviews were more likely to have favorable results (3/4) than non-industry sponsored reviews (1/23), RR: 17.25 (95% CI: 2.34 to 127.29), as well as favorable conclusions (4/4 vs. 15/23), RR: 1.52 (95% CI: 1.14 to 2.06). All reviews funded by competitor industries reported unfavorable conclusions (4/4). In 42% of the reviews (13/31), authors' financial conflicts of interest were not disclosed. Reviews performed by authors that had a financial conflict of interest with the food industry (disclosed in the article or not) were more likely to have favorable conclusions (18/22) than reviews performed by authors without conflicts of interest (4/9), RR: 7.36 (95% CI: 1.15 to 47.22). Risk of bias was similar and high in most of the reviews.


CONCLUSIONS
Review sponsorship and authors' financial conflicts of interest introduced bias affecting the outcomes of reviews of artificially sweetened beverage effects on weight that could not be explained by other sources of bias.
Cesare Maltoni Cancer Research Center, Ramazzini Institute, Bentivoglio, Bologna, Italy.|Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America.
Daniele
http://orcid.org/0000-0001-6156-6516
D
Mandrioli
Philip R. Lee Institute for Health Policy Studies, University of California San Francisco, San Francisco, California, United States of America.|Department of Orofacial Sciences, School of Dentistry, University of California San Francisco, San Francisco, California, United States of America.
Cristin E
CE
Kearns
Charles Perkins Centre and Faculty of Pharmacy, University of Sydney, Sydney, New South Wales, Australia.
Lisa A
LA
Bero
D001319:Authorship; D001628:Beverages / Q000009:adverse effects*; D001835:Body Weight / Q000187:drug effects*; D016265:Conflict of Interest / Q000191:economics*; D006801:Humans; D007600:Judgment; D010506:Periodicals as Topic / Q000191:economics; D017594:Publication Bias; D012109:Research Support as Topic / Q000191:economics; D012196:Review Literature as Topic; D012306:Risk; D013549:Sweetening Agents / Q000009:adverse effects*
D013549:Sweetening Agents