Changes in household purchasing of soft drinks following the UK Soft Drinks Industry Levy by household income and composition: controlled interrupted time series analysis, March 2014 to November 2019

Objectives To examine changes in volume of and amount of sugar in purchases of soft drinks according to household income and composition, at 19 months following the implementation of the UK Soft drinks industry levy (SDIL). Design: Controlled interrupted time series analysis Setting: Representative households (mean weekly number of households =21,908) across Great Britain Participants: Members of the Kantar Fast Moving Consumer Goods panel, a market research panel which collects data on weekly household purchases (eg: drinks, confectionery etc) between March 2014 to November 2019. Interventions: The SDIL, is a two-tiered tax (announced in March 2016 and implemented in April 2018) on manufacturers of soft drinks. Drinks containing ≥8g sugar /100mls and ≥5 to <8g sugar/ 100mls are taxed at 0.24 GBP/litre and 18 GBP/litre, respectively. Soft drinks containing <5g sugar/100ml are not subject to the levy. Levy exempt drinks, irrespective of sugar content, include milk and milk-based drinks, no-added-sugar fruit juice and powder used to make drinks. Main Outcome measures: Absolute and relative differences in the volume of and amount of sugar in non-alcoholic soft drinks, confectionery and alcohol purchased weekly by household income (<20,000, 20-50,000 or >50,000 GBP) and composition (presence of children [<16years] in the household (yes or no), 19 months after SDIL-implementation, compared to the counterfactual scenario based on pre-announcement trends and using a control group (toiletries). Results: By November 2019, overall purchased weekly sugar in soft drinks fell by 7.46g (95%CI: 12.05, 2.87) per household but volumes of drinks purchased remained unchanged, compared to the counterfactual based on pre-announcement trends. In low-income households, weekly sugar purchased in soft drinks decreased by 14.0% (95%CI: 12.1,15.9) compared to the counterfactual but in high income households increased by 3.4% (1.07,5.75). Similarly, among households with children, sugar purchased decreased by 13.7% (12.1, 15.3) compared to the counterfactual but increased in households without children by 5.0% (3.0,7.0). Low-income households and those with children also reduced their weekly volume of soft drinks purchased by 5.7% (3.7, 7.7) and 8.5% (6.8, 10.2) respectively. There was no evidence of substitution to confectionary or alcohol. Conclusion: In the second year following implementation of the SDIL, there were sustained reductions in sugar derived from soft drink purchases, but no change in volume of soft drinks purchased. Effects on sugar purchased were greatest in those with the highest pre-SDIL purchasing levels (low-income households and those with children). The SDIL may contribute to reducing dietary inequalities. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement Funding: NR, MW, and JA were supported by the Medical Research Council (grant Nos MC\_UU\_00006/7). This project was funded by the NIHR Public Health Research programme (grant Nos 16/49/01 and 16/130/01). The views expressed are those of the authors and not necessarily those of the National Health Service, the NIHR, or the Department of Health and Social Care, UK. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. NR had full access to all the data in the study and had final responsibility for the decision to submit for publication. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes 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, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data sharing: Kantar Fast Moving Consumer Goods panel data are not publicly available but can be purchased from Kantar Worldpanel (http://www.kantarworldpanel.com). The authors are not legally permitted to share the data used for this study however interested parties can contact Kantar WorldPanel representative Sean Cannon (Sean.Cannon@kantar.com) to inquire about accessing this proprietary data.