Estimating the health impacts of sugar-sweetened beverage tax for informing policy decisions about the obesity burden in Vietnam

Background Considered a “best buy” intervention to cope with the obesity burden, a tax on sugar-sweetened beverages (SSBs) has been adopted in more than 40 countries. In Vietnam, a tax on SSBs has been proposed several times (most recently in 2017). This study aimed to estimate the health impacts of different SSBs tax plans currently under discussion to provide an evidence base to inform decision-making about a SSBs tax policy in Vietnam. Method Five tax scenarios were modelled, representing three levels of retail price increase: 5%, 11% and 19-20%. Scenarios of the highest price increase were assessed across three different tax designs: ad valorem, volume-based specific tax & sugar based specific tax. In each case we modelled SSBs consumption in each tax scenario; how this reduction in consumption translates to a reduction in total energy intake and how this relationship in turn translates to an average change in body weight and obesity status among adults by applying the calorie-to weight conversion factor. Changes in diabetes type 2 diabetes burden were then calculated based on the change in average body mass index of the modelled cohort. A Monte Carlo simulation approach was applied on the conversion factor of weight change and diabetes risk reduction for the sensitivity analysis. Results While the impact of a 5% price increase arising from a tax was relatively small, increasing SSBs’ price up to 20% appeared to impact substantially on overweight and obesity rates (reduction of 12.7% and 12.4% respectively) saving 27 million USD for direct medical cost. The greatest reduction in rates was observed for overweight (23≤BMI<25) and obesity grade 1 (25≤BMI<30). The decline in overweight and obesity rates was slightly higher for women than men. Differences were evident across all three tax designs with a specific tax based on sugar density achieving greatest effects. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement DTN, HVM & SD received funding from UNICEF Vietnam to conduct this study under contract no. PO 43331943. The funders had reviewed the study design and commented on the final manuscript. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study was approved by the Ethical Review Board for Biomedical research Hanoi University of Public Health (no. 373/2021/YTCC-HD3 dated October 4th 2021) I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All relevant data are within the manuscript and its Supporting Information files.